1) Quest functionality and style will be much more in line with EQ1 (loot whenever, turn-ins later, repeatable, etc.) But there will be variance. Some quests will only be completed once. Some quests may only be open/active for a certain period of time, etc. We want to keep what worked well and build a bit of depth/nuance into it where we can.
2) We're not solid on this one yet, though my leaning is more towards Classic EQ. However, one thing I would like to explore is dynamic NPC response in these interactions. Not truly dynamic, of course, but I'd like for the NPC to react differently if he asks you a question and you get it wrong. Or, he presents you with two paths that are mutually exclusive - if you go down one, the other may never be open to you again.
3) Yes on the quest journal, though we'd like to keep it minimalistic and give the player the ability to write in their own notes.
4) It depends on the quest, but the majority of quests will be tuned more towards the physical/prestige reward of completion, not experience gain. Still being discussed, feedback here is very helpful to us right now.
5) Encumbrance is making a return to some degree, nothing concrete to share yet. We're exploring a vision skill, want to bring back a sense of racial identity through the way you see the world. Languages will be important again, as will research and reagents. I'll share more as I think of them.
6) Vendors will sell to others what you sell to them, absolutely.
7) Current Wiki is accurate with a few changes pending shortly, can't say more right now.
8) If there's an official name for the development process we're using, I'm not aware of it
I will do some research on the ones you mentioned though.