All those feats are solid for you, I personally Recommend Combat Reflexes and the first two snap shot feets. Be next to the party wizard and enemies will have a helluva hard time locking him down with grapples and the like.
Okay here's some things I always assumed with the fast reloading.
For some reason guns are ridiculously expensive in Pathfinder, and for some reason they are ridiculously easy to reload.
That's because you're not buying a freakishly expensive repeating pistol, you're buying 20 of them. The only other way to do it is to be in a western setting because only getting one attack every other round is absolutely terrible.
I really like your guide so far, but I have a few critiques.
1:You really undervalue wisdom. You really can't dump WIS on a class that has it as a bad save. A 12 is usually my minimum for martial types.
4:Assuming I'm doing it right...Invisible Blade lets me treat EVERY attack as a sneak attack, correct?
5:Critique Rogue talents too.
The problem is that Holy Gun and Divine Hunter are both terrible Archetypes, even if you were allowed to play them. Divine Hunter replaces too many good abilities with completely useless ones, and Holy Gun has the oddest written and worst possible replacement for Smite Evil while also hurting your proficiencies. My advice is to go Gunslinger 1(Mysterious Strange Archetype)/Paladin(Oath of Vengeance). Mysterious Strange uses CHA for grit and by spending 1 Grit you get CHA toattacks to go along with your smite, and Oath of Vengeance gives you a TON of smites. This effecively makes you Joshua Graham, so feel free to play the scariest Holy Man ever. If you really need the bonus feat at level 1 to get Precise Shot, Oath of Vengeance still stacks with Divine Hunter.
An issue is keeping your gun maintained as a Mysterious Stranger is that one of their abilities replaces Quick Clear, so keeping some scrolls of Make Whole are needed after a certain level. They should cost 125 each. Another option once you can afford it is to get Reliable enchanted onto your gun to reduce it's misfire chance.
1) What race combos better with this? (Samsaran comes to mind for MAD)
Samsaran are both thematic and good for your build. The Alternate racial trait will give you plenty of spells of both divine and arcane. Other options exist, of course. Remember you only NEED an INT and WIS of 16 to get all your spells, and your DC's don't matter too much since you're going to be using touch attacks mostly. Tengu is also an excellent option because..well..they're just great overall. If you choose Tengu get a Katana. Dwarves are also great if you can't be a Forgemaster otherwise.
2) Strength or Dervish dance? Second one is feat intensive
I personally don't like Dervish Dance, but you're only going to get up to medium armor as both a cleric and Magus, so a Dervish build is just fine. Your optimal armor is going to be either a Mithril Breastplate or Darkweave Studded Leather, depending on how high your dex gets.
3) Any new magic items I'm missing? And which ones should I get first?
Pearls of Power would help you greatly, especially if you choose Crusader Archetype.
4) Archetipes for either magus and cleric?
I would suggest Forgemaster/Crusader for Cleric to both lessen MAD and because the bonus feats help with Dervish Dance. For Magus I suggest Black Blade and Hexcrafter if you can fit your Arcana in nicely. Otherwise just leave it or go only Hexcrafter. Hexes to pick up are Prehensile Hair, Evil Eye, and Flight. Other Hexes either won't scale, get gimped by full round actions, or are covered by your divine levels.
5) Arcana suggestions?
Familiar if you don't go Eldritch Heritage, Arcane Accuracy is and Familiar Arcana are great. Grab Improved Familiar and get something great. Spell Blending is required for this build.
6) And what combos and gameplay do you guys suggest for this particular combo?
I would go Scimitar even if you aren't Dervish, but if you are not Dervish and can get proficiency with it without a feat(Tengu, domain), the Katana is excellent. You want to pick a Domain that grants a level 2 power that doesn't need to scale and is pretty good. If you go forgemaster your domain is artifice domain, which is okay.
Tengu aren't ideal? They get +2 Dex +2 Wis -2 Con, ideal for a ranged inquisitor in terms of stats, though yes, sword trained and exotic proficiencies is sorta bad unless you're going for a double crossbow or crystal chakram, since there aren't many good exotic ranged weapons.
Sword Train and Exotic training is pretty damn nice for a melee inquisitor, though the con will hurt there.
Also you provide many good AoO based teamwork feats for the archer, but these wouldn't work very well without snap shot which is also a great feat. Similiar idea with your fighter type builds, you suggest Martial Weapon Proficiency feats, when the prerequisites for that are the same as the ones for Exotic Weapon Profiency, BaB 1. Good Exotic Weapons to suggest are the Fauchard(best polearm) and the Falcata(Best One handed Weapon)
Sorry if I was unclear(I'm pretty tired at the moment) but I mean after Seeking, Reliable, and maybe Distance, enchanting a gun with stuff like fiery and holy isn't as worthwhile as it is for a sword. Getting flat bonuses to it is just fine. Keeping a bunch of Cold Iron Holy Axiomatic Bullets for demons and fey, silver for lycanthropes, holy and fiery for vampires, etc is a great investment and at mid levels(10+) you should be stocked with versatile rounds. Think about all the times you wish you had a ghost-touch weapon.
Your standard rounds would likely have a bunch of crazy damage bonuses like fiery and acid splash, but a small amount of special bullets is always good. The typical archer has a bit of an advantage in this market because of the existence of durable arrows, but enchanting ammo is pretty cheap(though one time use) compared to a weapon and you still use your weapons enhancement bonus when firing along with it's other properties,though they and the bonus don't stack with the bullets.
It would most likely work the same way a Halberd does, you enchant the whole metal bit, since they're not separated by more than an inch. However I would treat the stock of a Gun as a different "weapon"(ie a greatclub or something) and thus enchant that individually.
Anyway it's not really good to enchant the GUN in most cases, get +1's, only distance and reliable are worthwhile, all other enchants should go to your bullets.
Oh sorry. It's just the thread says long range sneak attack and you used the term sniper, I thought you mean some dude shooting from far away.
There are a couple ways to expand sneak attack range, one of them are the Sniper Goggles added in Ultimate Equipment, another is Ninja Tricks to increase it, and I believe there are races with that as a favored class bonus. Otherwise your DM can say "No this gimps your character" and say you're free to snipe.
It wasn't a copy/paste mistake. Eldritch Heritage is a great feat that gives you bloodlines. If you're in a CHA class or rolled great CHA there's a ton of bloodlines that usually suck for sorcerers that are amazing in other classes, like a Paladin with the Orc Bloodline.
My favorite thing about your guides is the roleplaying roles sections. I don't think many people do this and I was pleasantly surprised when I was first reading your Paladin guide. You also have a great selection of art and give input to many of the more "modern" feats we have available now unlike Treantmonk and RogueEidolon, who haven't updated their guides in years.
I like this inquisitor guide already, but may I make a suggestion for a Crossbow build? Inquisitors are the only class that automatically get repeating crossbows as a proficiency so it is at least somewhat an intended role and thus someone will want to make one. I suggest adding in commentary on the "Rapid Reload" and "Crossbow Mastery" feats, which make your crossbow reloads Free Actions and thus viable. A Crossbow build is also better at crit fishing and there is a Prestige Class where you add CHA to damage. I'm sure it's not as good as the Longbow Inquisitor, but it's certainly viable.
I'm going to be playing a normal archer Inquisitor in the near future, so thanks for the guide =)