How short are you? To have a "gut" at 100 pounds I'd expect you to be 4'8", so calm down. I'm sure you're mad skinny. (Is that what you wanted people to say?)

Navel piercings can take upwards of 6 months to heal completely. I've had mine for more than a year and it still crusts or can bleed sometimes if I catch it on something. Make sure to avoid baths, hot tubs, lakes, and swimming pools for at least the first 6 weeks. If thats unavoidable, make sure to properly clean your piercing after any of these instances.

it takes about 6 weeks to heal n if you are insecure about ur "gut" get the piercing n when it heals c if it looks good if not walk or jog, believe it or not it helps with ur stomach (i had a gut when I got mines n did this exact thing but I can't wear it any more cause I'm pregnant grrrrr) lol

4 like 3-6 months or a year :)

It'll look fine. And it takes anywhere from 6 months to a year to fully heal.

I've heard 6 months and you can't get into lakes,beaches or pools or it will get infected