If what you mean by close back up, is get tighter after intercourse, or the time it takes for your vagina to retract back after continuous intercourse, it usually varies with every woman. If you are looking for a quicker method for that closness or (tightness) of the vagina, you can always put vinegar in your bath water and soak for a little bit. This will contribute to bringing the vagina tighter.
It depends on how long you kept the stud out. If it is a new hole and it has been a couple of days, your hole will be a little tough to open back up. But if it is an older hole, chances are you have dry skin or gunk stuck in the hole.
Your belly button does not close. You are stuck with it for life.
if its a fresh piercing the hole will close up pretty quickly, if you've had it for a while the hole will probably take a while to close up
i have taken mine out and left it out a good two days and it is almost impossible to get back in. so not long.
Like one week
From experience, if it does get infected, it will close, or at least try to. If you decide to keep your gauges out for a while, yes the hole will shrink. It depends on how long you keep the gauge out of your ear.
Many times, the hole will close and you will to get it pierced again. However, sometimes you can still slide it in, it's a case-to-case basis.
Depending on how long you have had your ear stretched to a 0'.. If you have had it for years then it's unlikely it will close back up completely, but it the hole is fairly new, a year or so, then it will close up. It all depends on the healing process of your body. Everyone is different.
As long as the penis and/or semen is in contact with the vagina, there is the chance you may get pregnant.
It varies, if you have had the piercing for a long time the hole might never close. It does vary, i got my ears pierced over 3 years ago and still close overnight.
a few hours
As long as the body takes to minimize the piercing and close it, there is no magic solution that will make it close faster. It's just a matter of time.