Can I take Viagra and preworkouts after HT?

It varies depending on if you have FUT or FUE and other factors, but generally it's a few days before you can resume daily activities as normal. From there it can be anywhere from a week or two to a month before you can resume heavy exercise, etc.

Thanks for your photo and based on it you will need around 2000-2300 grafts to reconstruct the frontal part which means filling in the temples and lowering your hair line a bit. This amount will help to achieve a natural and good result with high density.

That's perfectly normal. Most transplanted hairs fall out between a week to a month after surgery, while scabs can take up to two weeks to fall. So, during this overlap period they often come out together, nothing to be concerned about unless you are picking off the scabs. However, you should...

This could take anywhere from 1000 to 2000 grafts, depending on your hair thickness, etc. which can't easily be determined unless you have a consultation in person. Average price is 5-10$ per graft for FUE, that depends on the doctor (and often larger procedures will come with a lower per graft...

Generally this is okay to do as long as you have waited at least a week after your transplant, preferably two weeks. Wait until the scabs have fallen off and you are healed before using hairspray on the area.

Transplanted hairs will turn gray in the same manner as your donor hairs will turn grey.  Surgery does not accelerate the graying process.