Q. With the introduction of EZdrummer 2, will we have to uninstall/remove EZdrummer and all the EZX libraries?
A. no.
Q. Or is this a completely new version with a completely different drum library that will coexist alongside EZdrummer (V1)?
A. it ships with its own sound library and will replace EZdrummer 1 in your projects (so you get the new upgraded version when you open them next). Pop/Rock will of course remain available.
Q. Is EZdrummer 2 going to be compatible with older EZdrummer sessions?
A. yes.
Q. Lastly, is EZdrummer 2 going to be compatible with the current line of EZX's, S2, the SDX's, Solo & EZplayer pro? Or are all of these getting updates to version 2 as well?
A. certain aspects require updates, in various respect depending on the product mentioned in your list. That will be done gradually but most will be available on release (of EZdrummer 2).
... feel free to post follow up questions, but be aware that we are planning to post a FAQ in the course of the day, or tomorrow latest, so you may be better off waiting for this to be posted and probe further points after reading it.