As for Carrie not looking like she's in her 20s anymore; well, what did you expect? Her appearance changes dramatically even from Star Wars to Jedi.

I highly doubt that they will be going for "beautiful princess Leia" at this point. Rather, if they take the EU into account, this is a woman who has been at war, with the galaxy and with her own government, for thirty odd years. She's had three children with a man who was not known for his stable, fatherly influence, and has undergone the rigors of becoming a Jedi, something that loses many people their limbs, and often their lives. The face that has seen all that would be a tad careworn to say the least.

I agree that they don't need Harrison, unless his character changes as entirely as Leia's should. I don't want to see the same characters doing the same things. They are beyond that at this point.