You can balance the individual colors using the bias and drive controls on the neck board. Note also depending on which revision neck board you have, there may also be an extra pot on the neck board to control brightness as well.
As for the sticking buttons, it can be a stuck switch, but also potentially a bad or broken component on the aux board, or possibly also a bad Pokey chip (also on the aux board). See the schematics, and look at the resistors and caps on each input, which are located on the aux board, as these often get smashed, and/or the caps can go bad, and cause stuck switches.
If any switch is pressed (whether legitimately, or if there is a problem and the board just thinks it's pressed), you will hear a tone, hence the constant tone you're getting.
You can try reseating the pokey chips (carefully, so as not to bend any pins). You can also try swapping them with each other, and seeing if that changes the behavior at all. Note you may see one problem disappear and a different one appear, depending on which Pokey is bad, and how it has failed. You may also get P or Q errors reported in test mode (which indicate a bad Pokey, though they don't flag all possible types of failures.)