These are both very complicated projects and not just "the basics." It will require some money to put together (bulbs for projectors can easily run well above $100). Most importantly however, the results are not likely to be very good. The screen on the DS is very small, and it's resolution is 256 x 192. If you turn this screen into a projector to blow it up, the image quality will be really, really bad. The resolution of the DS's touch screen is going to have about the same (if not exactly the same) resolution as the screen, so for that same reason, it will not be an effective mouse. You would not have the sensitivity required to do much of anything.
Bottom line, yes, these projects are possible, but no, you shouldn't attempt them. You'll only end up with a bunch of DS pieces. And please, please, please learn how to put together a sentence.
Dave