Do you have to wear a bra with it?

I'm 5'7", 145-150 lb, 32 band, 38 bust, bought the size medium and I do not wear a bra with mine. I do not think I could fit a bra under it tbh, it's a tight fit for me lol. There is no padding so if you're worried about nips showing, yes they will

Does it control upper back fat?

Mine arrived today 5/6. I am lower 180's with a lot of back fat and by golly this baby smoothed it out. I can't wait to wear this under my Luxx waist trainer.

Does anyone know if this control is as firm as their firm control camisole? I want firm control but I prefer a tank over a camisole.

Yes it's very firm I love them I myself got two of them

I'm a 5'7 weight 160 and a 36ddd woman . what size should i order .

I'm 5'3" 100 lb, 34 C. I tried a small and I couldn't get it on and off myself. I just exchanged for a medium. Better, but was still hard to get on. It is shapewear so intended to be tight, but the small was crazy tight for me. I'd recommend ordering a size larger than you would usually wear. At least I had to.