Welcome back.
First, I'll let you know that every question you asked can be found in these forums already and has been asked about 100 times...so hopefully you can do your research.
Second, I'll work on getting a few links from threads regarding your questions if you're incapable of doing your own research, but it may take me a little bit.
Third, I don't know the current situation of the p2p server as I haven't seen any new threads regarding a massive influx of players since the 7.0 patch released less than a week ago, however, people have stated they were going to be coming back. The population, in comparison to the f2p server, is minuscule however. No one knows the exact numbers, because my.com refuses to share with us for reasons unknown, however, I would assume for every 20-25 players on the F2P server there is 1 on the P2P server. - Before anyone freaks out, I am not bashing the P2P server as I think a small population can be a good thing (other than when drama happens...because then there is no where to go to avoid it), I am just stating it is significantly smaller than the F2P server's population.