The Sandpoint Devil's page

You don't have to house rule it. A strictly melee weapon is an object that was not crafted to be a ranged weapon, so the feat can apply in this instance.
But you are stacking non-proficiency penalties as the -4 from improvised weapons is a non-proficiency penalty. You are either proficient or you're not. You can't be doubly non-proficient.
So your Throw Anything Alchemist would be able to throw a Large Bastard Sword at -4 non-profiency and -2 inappropriately sized (total -6) for 10ft. dealing 2d8/x2. With the feat, the alchemist could throw it for -2.

For the octopus (size small) refer to page 6 of the Bestiary under the space/reach entry: "if the creature's space and reach are standard (one 5-foot square and a reach of 5 feet), this line is omitted."
So the small octopus can only reach 5 feet with tentacles or bite.

Since there isn't a frog (small size) stat block, I am unsure of what you mean? But you could take the frog (medium size) and apply the Young Creature template on page 295 of the Bestiary which would reduce the frog to small size though this wouldn't reduce it's reach. If I were the GM, I would rule that the size reduction would reduce it's reach to Reach 5 ft. (10 ft. with tongue), but it is not that big of a deal since Small creatures can only swallow Tiny creatures.

It is plausible to obtain the Poison Frog as a familiar though I would think you would need the Improved Familiar feat to get the Giant Frog. The Core Rulebook states under the Familiar entry that "A familiar is an animal chosen by the spellcaster" and that "Only a normal, unmodified animal may become a familiar" which the Poison Frog is.

Furthermore the Bestiary states under the Familiar entry that the familiars presented there are only the "most commonly used familiars", so they aren't exclusive, and from these entry's we can infer that a prospective familiar must be no larger than tiny and cannot have a CR greater than 1/2. The Poison Frog qualifies there too, so really it's just a matter of determining what special ability the Poison Frog grants and applying the changes under Familiar Basics sub-entry in the Core Rulebook.

I'd suggest, considering the Poison Frog has a Constitution draining poison, a situational dependent bonus: "Master gains +3 on Acrobatics checks when jumping". But as always, the GM has the final call.

Oh, and there is no reach for the Poison Frog because it doesn't have the Tongue Special Ability.

Well, I did say I combined the two, but more specifically I took the opposed rolls of 3.5 and the uniformity of pathfinder. In 3.5 you always had to check the special attack to see if it was an attack roll or a strength roll or something else altogether. In addition, I accounted for Dexterity which PFRG only accounts for on the defensive end and 3.5 only accounted for on the defensive end of Overrun and even then you had to choose between Dexterity and Strength. It's not wholly new; it's slightly adapted hence a houserule.
Furthermore, I can always take 10... I'm the DM, but then to be fair I'd have to allow my players to do the same which would make the outcome a forgone conclusion, and time wasted as an indecisive player decides whether to roll or take 10. It's just easier to remember one bonus (or possibly a negative) and let the dice fly. Plus when we roll out in the open for a combat maneuver, it feels like a contest, and combat maneuvers almost never need to be fudged so there is no reason not to.

No, he shouldn't get an AoO per the Core Rulebook page 187 under the Cast a Spell Entry fourth paragraph: "You only provoke an attack of opportunity when you begin casting a spell, even though you might continue casting for at least 1 full round."
Now that doesn't stop the attacker from using a standard action to cause damage and disrupt your spell, but that someone isn't getting a freebie either.

Unlike a basic attack or a spell, combat maneuvers are confronted by an opposing force, but the current combat maneuver rules lack some of that flavor. Combat Maneuver Defense feels like another form of AC with a different outcome, and it annoyed me that the Combat Maneuver Bonus ignored Dexterity.

I have been testing a house rule that adds that flavor and provides my PC's with a sense of agency. It essentially combines the PFRG approach with the 3.5 design. All combat maneuvers are opposed rolls using CMB except that CMB now adds Dexterity, and they still provoke attacks of opportunity.

CMB = Base Attack Bonus + Strength modifier + Dexterity modifier + special size modifier

The only thing you have to watch out for, depending on the combat maneuver (bull rush, drag, trip, disarm), is whether the attacker won by 5 or more or lost by 10 or more.

I have found in play that combat maneuvers are resolved quickly this way especially since the rolls are simultaneous and CMB's don't change as often as other forms of attack and the results are on the table. As a GM, I have found that the extra d20 roll is worth not having to check a character sheet for CMD, and players only having to remember one number. Because of this, player's are more inclined to try combat maneuvers which breaks the monotony of basic attacks and adds variety and spice to combat. On the receiving end, they enjoy getting to roll defensively rather than an automatic result especially if their foe has the appropriate improved feat.

On the flavor end, grapples now have a sense of struggle, and that sly rogue can disarm as well as the hulking barbarian. I have also added feint and parry (from the duelist prestige class) as combat maneuvers, so they use CMB instead of their standard ruling. Is anybody else tinkering with combat maneuvers?