Frankly I'm kinda split on this:
The ending of K1 left me wanting to know wtf happened to everyone, so I'd like to know that. I also don't want to have the people from K1 dropping dead left and right in the five years between K1 and k2. Thats kind of unimaginative and empty story telling. I also don't want them to "pass the buck" on the fates of K1 peeps to K3. Plus I'd enjoy just continuing the story from K1 with the same party.
On the other hand, it presents a design problem to have PNPCs from k1 to join you in k2. I mean, do they magically start at level 1minus all their past abilities, I mean you can start them at level 17 or something (which makes me curious about how t3 and HK will be "powered down"). I also like the idea of brnd new characters and stories to tell.
I think I like the idea of the droids returning, but I would like to see 2 PNPCs from last game join you but which one you get depends on your revan answers. As fpr the remaining npcs, tell me what happened to them or have them as cameos.