Kitchen_bench,
I did my FSP about a month ago and arrived with about 3 hours of flight experience (and these three were done over a year ago, so it might as well have been no previous experience).
I reckon that you don't need any previous experience, as they really do teach you everything up there anyway. The only reason you'd want to get some hours up would be to show enthusiasm, but even then you can show that through your job research, going to air shows, talking to pilots and stuff like that.
And yeh, most nights (and days in the crew room when you're not up in the air) are spent reading your notes, drawing your ciruits, chair flying etc.
Best of luck