Screen size: You didn't give information about your monitor or video card so it is hard to know exactly what is going wrong, but this certainly isn't a common problem. You might want to look at the cheat codes section of the wiki (follow the documentation link near the top of this page) or read the cheat codes text file that comes with torrent downloads and use a cheat code to force a screen size for something suitable for your particular hardware.

As to the mouse, again not a common problem and I'm very surprised that you would be seeing it on several systems, particularly with a PS-2 mouse (although a USB mouse should work too as long as it is connected at boot time and you are not going through a KMV switch that switches between computers (these ofthen confuse my mice under Windows)). Even laptop touch pads tend to work in general, although on those you have to use the buttons to click, not tap the pad. And I've had good results with both video and mice with other distros also, particularly Puppy. DSL is rather dated, I would not judge live CDs based on it.