I'm fairly certain Sony has said that they will make the games playable on the PS3 in the future. It would make sense since not every PS3 owner may have a PSP, and the system itself would be perfect for playing them on (especially games that used two analog sticks).
I wouldn't be so sure about that. If they can get the licensing rights to put them on there I think they'd do it. It would be easy enough to break the games up into multiple downloads, especially since they're divided up into discs already, to make things a little more manageable. The file size for a single disc would be comparable to the file size of the PS3 demos for Motorstorm, Gran Turismo, Formula 1, etc. which are all available for download in the playstation store right now. It would take up a few gigs of space in the end, but if you ever needed that room, you could always delete it from the hard drive. Sony's already said that people can re-download something they've bought through the playstation store at anytime.