Trouble with Macbook display -- brightness cuts out or gets wavy if I move the screen around
As a former Apple technician in a retail store, I can tell you that if an SMC reset didn't fix the "stage lighting" display issue, we replaced the display assembly.  Probably not possible through Apple anymore since a 2008 MacBook Pro would be considered vintage...

For the keyboard/trackpad issue, you might try reseating the flex cables underneath the top case.  iFixit.com has great guides for opening up your Mac. You open your computer at your own risk. :)  If that doesn't change anything, could be a bad top case.  The keyboard assembly and top case are separate on the 2008, non-unibody MacBook Pro, so then it's up to component isolation.

Summary: Don't spend any money fixing this computer (unless you reeeeeally want to).  Like an older car, it can be difficult to find parts for older computers, but there are places that have them.  My advice would be to use it until 'till you lose it, then purchase a new computer.