Couple Questions about a Trox Blitz Soldier with Power Armor

[OpSkillMonkey]

Yes, it's probably ridiculous to some degree (or many), but I am building a tanky Outlaw Trox Blitz Soldier with Power Armor. I'm a new to the game but not to roleplaying, and I have a couple questions that I would like some help on.

Base stats: 13 STR, 18 Dex, 12 CON; 10s for the rest.

(1) Can any power armor be given to a player of large size or only those armors designated as Large or Gargantuan? If you are a GM, would you permit a Medium size armor but at a higher price (reflecting modifications)?
(2) Can a burrowed creature attack from cover underground in melee while still burrowed? If yes, would AoO still apply when burrowed?
(3) Does reach of power armor stack with the reach of the racial reach of the Trox?
(4) I've looked at most of the guides for Soldier builds, but are there any feats that you consider MUSTS? Or, any that you highly recommend for such a build?
(5) Are power armor weapon slots only for ranged weapons? Or, can I add a weapon like a chain or sword as integrated?

P.S. From a character story standpoint, Bok is an outlaw because the Hylax's followers--especially Bok's clan--are actually a little more culty, vengeful, and violent about "Dissenters of the Peace" than you might think! And, the "emissaries of peace" might be framing and hunting him. This forced him to pursue paths he might not have otherwise gone down.

[HammerJack]

Let's see...

1) There is no consensus on this part, so you'll need to ask your GM. I would work out a large version of the armor, but that is only my answer, not THE answer.

2) This sounds like a no, to me. The ground between your hands would by blocking for your target. But you also wouldn't provoke from most things moving under them. But I believe that the powered armor replaces all your movement speeds with its own, and would not be compatible with burrowing.

3) No. Large power armor with a 10 ft reach is not armor with a "+5ft" reach. If your GM wants to make a huge version of a suit that's normally large, as an approach to making them Trox sized, that might have a longer reach.

4) There are plenty of good feats, like coordinated shot, since you have a large threat area.

5) Those slots are for ranged weapons.

[Garretmander]

1) Powered armor says that it is designed for use by medium or small roughly humanoid creatures. Creatures not matching those descriptions use the rules on PG. 196 CRB for adjusting equipment to fit.

5) there is, I believe, one suit of powered armor with slots made for melee weapons, and only one.