#1: possibility to set another screensaver that will run after defragmentation has finished.
Great idea, I like it! I've put it on the wish-list and will try to add this to the screensaver in the future.
#2: some kind of counter, how often a day screensaver-defragmentation will run.
Well, yeah, but suppose you set it to 5 and all five times are used up within two hours of turning on the computer. Then the rest of the day nothing would happen. Hmm. Perhaps a setting "NN hours between defrags" would be better?