Welcome back - spandex is always better than chainmail 
Server populations are much the same as before, but I'd suggest you join the main server chat channel of whicherer server you choose, as it'll help you communicate with everyone else.
If you're on Defiant server, then the channel is called Defiant Events, and /chan_join Defiant Events is the slash command to join it.
The game is sitll very solo friendly, although the new Incarnate endgame system that they've started adding is designed with teams in mind.
Joining an SG isn't vital, but if you're more of a team person, you might want to join one.
The old content can still be played, and you can even switch sides now to see everything the game has to offer.
There's way too much that's happened in the 9 Issues you've missed, so go to this link, click the Issue numbers, and get a run down on what each one brought to the game:
http://paragonwiki.com/wiki/Issues
We've gotten everything from walking and costume change emotes to new TFs and player-created content via the Mission Architect.
@Golden Girl
City of Heroes comics and artwork
Hello all,
Been a while since i've played but just got support to re-activate my account.
Still having a bit of problem getting my account and password to be accepted but I got the support working on that.
Anyway . . . .
Never got to the end game as I always ended up the playing the blizzy game!
So I have some questions . . .
What are server populations like now?
I have just upgraded to going rogue to get my 30 days play.
Can i still play the old content, is it still necessary to play it?
I think the last update i saw was about i10 what have i missed?
Can you solo, is it easy to find teams if necessary? is being a member of a super group vital?
There prob plenty more questions but really need to get my log in sorted.
Hopefully see you in game very shortly
Cheers
Ian