I've got a pre-face signum and one of the rear numberplate bulbs has gone. So i went out to check what bulb i need, an easy job or so i thought.
But where there used to be screws there is now just a crumbly mess of rust.

I'm assuming i'll have to drill out what's left of the screws, but what size screws do i need? the lens themselves look a bit yellowed and tired, so are they cheap enough from vauxhall and do they come with screws?
And finally what bulbs can i use? Ideally i'd like some bright LED's but don't know if they'll cause issues with warning's (i'm assuming not since it's not warning me a bulb is blow at the moment)

Sorry for all the questions, but time is tight before the MOT and dont want to be going back and forth with lights hanging by wires.