Yes definitely gear your left side with Poetics first. It will be a tad bit slower, but it'll work out. Accessories have much more leeway than left side armor and weapon.

I am a fan of using Str when I can get away with it, but I also fully recommend using Vit until you're comfortable. Vit accessories are still handy in speed runs in dungeons if you have a group with an ae dps composition. If I'm pulling big, I use Vit. If I'm doing small pulls, I use Str. But I am i117/ i116 depending on set.

As for T5.. Gearing up enough for T5 at this point is very easy. I'm sure you're probably geared enough already, though I haven't seen your equipment. That fight is entirely about the deaths that occur from Divebombs and Twisters. Death Sentence used to be brutal, and I suppose it still could be without experienced healers. Get used to using CDs for DS to help.

Mostly, just research T5 and try to learn the fight. That fight is all about knowing more than just overgearing for it.