Agust, you should know the last part of question #5, you're good at making new themes.
#4 Not real sure that is possible in E17, might have to google that one. Pretty easy with compiz but E17 doesn't run with compiz enabled, at least not without some work.
#2 For this maybe log into KDE (if that's your main D/L desktop), make adjustments there for "never", log back into E17, or maybe you're describing the x-screensaver and it's settings?
#1 It's in a configuration screen,but been so long I honestly don't remember. It was irritating to me too,rather use compiz,window switcher in the panel, or the right click option for Gnome.
#3 It's in a configuration section also.