Hey ! It depends if you are taking it via your mouth or backdoor - I do it via the later and yes it does feel like that, when the farting sensation is un-bearable that's when you should let out - or if you start getting really bad cramping.
I don't think it increases your eating capacity as you're only putting a little extra air on there. You will strech out over time inside, but after inflating it should return to normal (like a balloon being deflated )
As you're not actually increasing the size of your stomach permently then your eating habits should stay normal ! If you want to gain eating capacity then I'd suggest just eating more regularly and larger portions ? But you might get really fat haha !
Probably. No.