Screen - likely nothing you can do about it, since it's a progressive age thing. However if you can find a new screen, it should improve.

Buttons - disassembling and cleaning the remote might help here. Note that you need a #7 Torx screwdriver (#6 also seems to work), and remember that there's a screw under the label on the back.

There's some tips on disassembly here: [Link: remotecentral.com]