Hi, I will try to help to the best I can since not very many people seem to like giving advice on this PrC on account I've posted like 3 threads on various questions and almost never get answers.
-The first one greatly depends on your abilities. As written, you can posses objects and animate them before 6th level but without that last level you can't control that animated object as it becomes a 'creature' after animation. Doesn't help that technically they get a Will save, but at least you can order them not to resist. It also helps if that suit of armor or whatever has a pair of gloves which some don't.
-As before, you have to be in control, which then makes the suit of armor your new 'body' so yes you can use various combat maneuvers. Just remember that its based off either your total HD or Sorcerer levels + FoP levels (which ever is higher) to determine the Caster Level for when you cast Animate Object. At 20 HD you have 20 rounds without re-application. Along with the fact you have the duration of your Control Creature of FoP level + Cha mod + 1 for each previous control. So if you take some down time with a specific item you can eventually be able to control it all day...
-Yes, somewhat like DR in that regard.
-Technically all mind-affecting spells can affect you as you are in control and am treated as if you are the one resisting. So an innate mind-affecting resistance/proof is necessary if you don't have a high Will save.
-Then in many ways you are going to be treated like a Construct, able to tank without worrying about being mind controlled.
Something I find extremely funny is placing Curses on the items I possess so that whenever I hit (or surrounded with a pool of water/cloud of dust) someone a specific Curse would go off. There are quite a few good curses out there if you know where to look (Dragon Mag #348, PHB, & Book of Vile Darkness being the key ones).
Hope this helps, [insert shameless self promotion] and if interested why not stop by for a lookie see at my version of this wonderful PrC! [/insert]