@Grug16 Heh, welcome to the club. That's what got me and where I started. I've since transitioned over to the Thrall Server, alliance side if you wanna look me up 🙂
1, Ascension is the guys who run the servers not the servers themselves. Conquest of Azeroth is one of the servers (specifically the one that has the 21 classes).
2, There is only one server that has the 21 classes you only have access to it if you purchase it otherwise Thrall and Area 52 that are free, the former is a draft mode ability pick (every two levels from 10+ you get three abilities at random pick one), the later is pick any ability as you level to take. I can't remember the servers name that has the 21 classes while they were fun the server wasn't super populated and currently still has a level cap (going up periodically). I sign in periodically check out the changes and go back to Thrall for the community.
3, It's available immediately
4, you can buy different amounts of DP via a drop down menu, yes you will need 50.
5, You can find some of them in the online store but TBH your better off logging into Thrall and finding them there as most if not all of them are on the AH and you can see them quickly via searching there, or like I said msg me on Thrall and I can help you out with that there.
6, you cannot, when you buy the items in store they will be delivered to whatever character you have assigned. That being said MOST of the items get added to your vanity ingame so you can then give them to ALL your crated characters (with some exceptions).