1. you can do moderate reshaping of the neck.
2. Talk to your local trphy center or some key cutting places about engraving. Also gun shops if you want really fancy stuff.
3 RealParts had some engraved tele bits
4.h As Waz said don't sand the veneer. I haven't sanded any of mine, clear coats will grain fill and level it .
5 Best to test fit everything before any finishing, that way there is less chance of accidental damaging of your finish. Most aftermarket pickups and bridges will need some slight work to make them fit. Can be achieved with sandpaper on a dowel or a dremel tool or sanding drums.It's not much material to remove.
welcome to your new addiction ;D