Yes it can. It all depends on your body. No real way to tell how long it would take.
No. Go talk to your doctor if you want the piercing to close up that badly. Over time the piercing will shrink and will become unnoticeable
After 3 years chances are good it wont close, the piercing will shrink but not close completely.
It depends on where it is pierced. The lobes can take about 3 months to completely close up, where your cartilage can take 6 months to even a year to completely close up. It also depends on how long you have had the piercing. A piercing that you've had for years can take years to close (in my personal experience).
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.
If you've had the piercing for only four weeks then yes, it will close relatively quickly. My lip piercing was two years old and closed up in only a few days, leaving a small scar. If you don't want it to close but do want it to go unnoticed look into piercing retainers.
Well if you have had the piercing that long it won't close, however it will shrink over time. The mark left by the initial piercing will remain in place and will look less noticable over time.
Plastic surgery
There isn't a way to tell :/
Well, its really hard to say because everyone's body will react differently, and it depends on how your body heals. A tongue piercing is considered an open wound right up until you let it close. After five years mine is still considered that. I have had mine for about five years now and I'm so used to it that when i take it out, i forget. I have gone a little over two weeks with it out and it didn't close or get smaller. I had a tongue ring for close to four years and it took a couple days at most. I don't think it actually matters how long it's been once it has been more than a year or two.
It doesn't matter the location and age of the piercing...some of them will close in a matter of minutes and some will never fully close.
stitches...
It really depends on the size of the piercing and how new it is, the larger and older the piercing happens to be the longer it will take to shrink down then slowly close and heal up. You could be looking at anywhere from 3 months to a couple of years.