This. I would be very pleased as well.

Part of me just wants to beat up Sephiroth as Gabranth.

That would be so satisfying.

isnt ff13 supposed to essentially be done? they finished the story and something having to do with the characters interacting (forgot the name). all thats left would be gameplay, graphics, and voices besides the minor polishing of the story.

should they be able to add a ff13 character as the characters themselves are set in stone?

The PSP is capable to handle DLC, so I dont see why couldent they just add them later ;)

Yes, it is very possible for Downloadable characters. PSN is now much more PSN friendly then EVER before, it makes the PSHome/PSP/PSN/PS3 link up much more connected and easy to use.

Looking at its JP 2009 line-up, it appears more alive than you.

As for Dissidia, I read there will be FFXII characters, but no one from FFXIII. Just read that Idol Master SP will have weekly DLC, so I  guess SE could use that route in the future...