1 - files\languagebank\english\gamecore\text, this is the directory to the tga files, just change them to display a different message. To get rid of them go to the dooruse, doorremote etc. scripts in scriptbank and delete the HUDSHOW command, just remember to keep backups.
2 - you have to import the direct x file into a modelling program and animate it yourself then search for melee on the forums, find a melee weapon then just copy the gunspec and change it for your weapon.
3 - only entities can follow waypoints
4 - there are water decals available on these forums or go to xplosys' site
hope that helped
so what's the job?