I run one on a 8 gb debian server from hetzner and it seems rock solid so far from what i can tell with the amount of traffic i am likely to have (just friends get an account). Running azerothcore and not trinitycore. Setup was very easy.
Quests are really just entries in a mysql database so im sure there are open source quests you can just inject into the database. or you can make your own :)
I am also running my own instance of azerothcraft on a vps so that i can play with some friends. Love it so far but summertime means there is not too much activity yet. Im running with autoscale mod and it is quite fun to run some of the lower lvl instances at lvl 60 and it is actually a challenge (yes i capped the level at 60 because that is what i know)
Anything in particular you like to do with your awesome gm powers? (moonfire spam wins)
Parsley. Absolutely disgusting
Edit: i misunderstood - for the record parsley is awful in all shapes and forms
And if I don't it's because I've misplaced it, and the program isn't going to help with that :(
In that case it will help you with where it was supposed to be
Yes you can use the autoscale mod to make content soloable but you might want to tweak the settings to get it to a difficulty level you like. Some raid bosses have some game mechanics that make soloing difficult though
You should look into the gm commands to see what you can manipulate and also the server configs have a lot of things you can tweak that could make the game more enjoyable for you