I've been playing Moria for a while now
(Yeah NDA was lifted)
You guys are in for a treat. The legendary weapons are awesome - they start off pretty wussy, but adding relics, levelling them up and reforging, is a helluva lot of fun, gives you something to work on while you're questing and farming.
Tier six crafting is a bit more complex, I haven't done too much with it - there is more variety of materials you'll be working with.
As for the zones themselves: the bulk of what you'll be doing is in Moria itself and it is massive. I think its about the size of Angmar, but the mazelike nature of it, and the density of content inside, means that it feels larger - and there's definitely much more to do in there.
Eregion's more of a filler zone really, there are a few quest hubs but Moria itself is where you will probably spend most of your time.
I can't answer questions about PVMP really - or raiding - I was more just casually testing - but there'll be plenty of discussion on the official forums now that NDA has been lifted.