PR Driver's License is valid for how many years?

I think it was recently enacted that PR new licenses will be good for 8 years. Old ones are to be renewed when they expire and the new ones will be for 8 years.

I do not see what the issue is o with the expiration as you then renew.

As to your other questions, I do not know.

I got my dl in April and was given 5 years and 4 months.  The thing is they do the expiration date based on your birthday and not when you received the license.  So how much time depends on your birthday, mine is in August.

If it expires you will have to do the written and driver's test all over again. Which they charge for.
Yes you have to go in person and you cant don't online. Also you will want to get a real ID. Which is a pain in the butt and a lot worse if you are a female that has changed you last name from your birth name. I have no idea as to the amount of time you can apply for it before it expires.  However if you dont have a real ID. I dont think it's an issue if you apply before your license expires.  I suggest driving to the dtop at 1 o'clock and talk to them.