For a TROLL I'd say no armour, use statue form or dragon form (since you are UC anyways taking up Tmut is a good move). With Ogre's whole -2* UC and 3! Maces I wouldn't necessarily do that.
Anyways, in my book due to your generally low defenses for much of the game Large Shield + Morning/Eveningstar or Demon Whip is better than the 2H G(S)C; it also has the luxury of NOT taking insanely high skill to get to mindelay. And a Shield (especially if you find one with rF+ or AC+3) is a significant help in your defenses.
As for armour: Early game, make a Steam Dragon if you kill a Steam Dragon (and that can be your permanent armour); otherwise stick to robe or troll leather.
Late game...yea, don't hold off until Holy Pan and try to get a PDA (Since they virtually don't exist outside of that one floor of Pandemonium and that floor is really hard). But my personal choice because of high Og STR is Shadow Dragon. The stealth really helps in extended. Though anything Shadow and Storm or lighter is fine; FDA/IDA in particular can help with holes in your elemental defenses. If you're trying to get level 9 spells online though, stick to steam/robe or take a lighter dragon like mottled, Swamp, etc.
I would almost never recommend GDA, the STR requirement to not make your EV nothing is stupidly high and unless you are with Chei you just can't cast in it, period.
I'm beginning to feel like a Cat God! Felid streaks: {FeVM^Sif Muna, FeWn^Dithmenos, FeAr^Pakellas}, {FeEE^Ashenzari, FeEn^Gozag, FeNe^Sif Muna, FeAE^Vehumet...(ongoing)}