Does the “control freak” plastic thingy come out of the downtube so I can get a new zip tie around the internal cables? I had to replace a cable so the zip tie obviously had to be removed.

It does on my slash, just a tiny hex bolt. That said, it’s only a finger size hole, so not sure how you would get a cable tie in,

Yep. As above.

The lower covers just drop out when you snip the cable ties… getting the new cable tie to go around all the cables/hoses in the frame however is a complete arse (from my attempts!).

Yes.

Use a spoke to fish it back out again to make you life easy.

Also worth folding the end of the ziptie to help as well.

Cheers. Nothing dropped off when I cut the existing zip tie. Might just need some waggling then I guess.