Rapid Shot: It says I spend a full round action to get off an extra attack (with both attacks at -2). Nowhere does it say the gun has to be loaded first.
The gun must be loaded to fire. So at the beginning of the day or whatever, load your gun. There are no rules for powder getting wet or whatever, so just like a crossbow, most DMs will assume that weapons are loaded. Some DMs may rule otherwise (the arrow falls out if you sling the weapon, etc.) so it never hurts to ask in the beginning.
As well, are both attacks aimed at the same target, or can I split them between two different targets? Are there more penalties associated with this?
You get one extra attack, you can make that attack against any legal target. Any existing penalties (or bonuses) that apply to attack rolls will apply to both attacks. (As well as the -2 from the feat)
You will need to reload the musket between shots, however. If this is not a free or swift action, then you will not be able to use that feat until it is. (I believe at level 1 you can reload your musket as a standard action)
Feats and skills: As a human, does grabbing level 1 of wizard mean I also get my bonus feat and skill? The actual wording doesn't differentiate between class or character level.
You get your human bonus feat at character level 1, which happens once only. You get an extra skill rank to spend at every level.
Guns: Both classes get a starting gun. So, does that mean I would have two muskets? Or is it that I already have one, I don't get the second one?
Not sure. I think you would get two. Which, if you have quick draw, might help with your rapid fire feat problem. (Fire one mustket, drop it, quickdraw the second one, fire it.) You would then have to reload one (standard), stow it (move), pick up the other one (move), and reload it (standard), which would take 2 full rounds.
Unless you have some ability that says otherwise. I'm not too familiar with Gunslingers.
HP: Related to the above, since it's society play, and first level, do I get the max HP of 6?
No. From the PFS Guide to Organized Play, Page 6, Table 2–2: Hit Points by Class: "* Your character gains this many hit points for his first level, not his first level in each class should he possess levels in
more than one class."Level 1 Gunslinger gets 10 HP (+Con bonus, +Favored Class if applicable)
Taking Level 2 as Wizard gets you 4 more HP (+Con, etc.)
There are no rules for powder getting wet or whatever, so just like a crossbow, most DMs will assume that weapons are loaded.
I am incorrect.
"Black powder becomes useless when exposed to water, but powder horns and cartridges protect black powder from exposure."
So it can certainly be ruined, though once it's inside the gun I still think it's unreasonable to say that rain makes the loaded charge no good. (There's wadding and a bullet in the way, for one) Some DMs may rule otherwise, though, especially as the Gunslinger is new and many people don't like guns in Golarion.
That does remind me of cartridges. If you're using cartridges it'll reduce the reload time by one step, so at level 1, with Rapid Reload, that'll be a Move action to reload, not a standard. If you have a double-barreled musket then that solves a lot of your problems. Shoot it twice, spend one round (2 Move actions) to reload both barrels. You can't get one for free, though, I think.
A Musket Master isn't a class, it modifies the gunslinger class, it doesn't get another weapon, she "must take a musket when she chooses a battered firearm at 1st level" as stated in the archetype.
He was asking about the Wizard Spellslinger archetype, which grants the Gunsmith ability, which in addition to granting the feat (which wouldn't stack) also grants a battered firearm. I'm not certain if the ability itself would stack and grant a 2nd gun, though. That might need an official PFS ruling. (At my table, if I allowed firearms, it would stack)
So, if I start the round with my gun loaded, can I then shoot, reload as a move and shoot again as per the feat?
Nope.
To use Rapid Shot (or to get more than one attack in any case) you need to full attack. To use Full Attack is a full-round action. If you use a full-round action, you don't have a spare move action to reload in the middle of it.
Rapid Shot is excellent if you have a way of reloading as a free or swift action. Otherwise, not so much.
-edit-
Fast Musket (Ex) at level 3 makes reloading it like a one-handed firearm (Standard action) which Rapid Reload makes a Move action. An alchemical cartridge reduces that further to a Free action. At that point you can make as many attacks during a round as you can normally.
OK, so let's just get this straight:
Musket Master with quick reload and alchemical cartridges reloads as a move equivalent action.
So, if I start the round with my gun loaded, can I then shoot, reload as a move and shoot again as per the feat? Otherwise I'm very confused because from my understanding, you get 1 standard action per round, that's all. And since firing is a standard action, how would that feat even be used? (especially since it's a recommended feat in almost any discussion I saw on gunslingers)
Basically it is as grick said. You have to invest alot for rapid shot to work with a gunslinger, but once it does it is rather good.
If using Mage Bullets, do I need to worry about spell failure rates to sacrifice a spell to get the enhancement?
Mage Bullets (Su) is a Supernatural Ability, as such it does not involve arcane spell failure (it's not an arcane spell).