Hard drive questions

[Gamekid]

1) As of right now with internal non removable hard drives, like the kind we all use in our desktop computers, if files are deleted off of the hard drive, it is possible to get the file back. Since the ps3 will come with a hard drive, will it be possible to get files back on the hard drive?

2) The hard drive is designed to cache files on it. So if you play Stranglehold, the files are copied from the disc to the hard drive and then to ram as they're needed. My question is that between a 20 and 60GB hard drive, will that affect game play performance. Here's the thing, if you play Stranglehold, would gameplay be affected on a 20GB hard drive vs a 60GB hard drive since files would be stored on the hard drive and then copied to ram?