Thunder 1a Fretless upgrade questions

Hi all

I recently picked up a nice black fretless Thunder 1a
My first fretless, I really like it.

I wondered if any of you can help me out with the following:

1. The nut is broken at the G, do you know which nut I can buy to replace this? I think I'll try and diy this one...

2. I always put a Badass II bridge on my basses.
Нas anybody in here replaced their Thunder bridge with a Badass or similar? Wondering about screw spacing.

3. The previous owner has draw gold lines on the neck.
I feel like these will wear off as a I play it but is there a trick substance I can use to remove these?
It's like gold sparkle pen, and the lines are wonky.... :-)

Any suggestions and help greatly appreciated!

Thanks

T