Been repairing my Mk1 RS and it's turning out to be more work than i expected! Front wings are off, and there are more problems underneath...

First issue: the air intake hose under the front left wheelarch -how do I find the part number for this hose as it's perished.. Also, if I get something like a Gen 2 K&N induction kit, will I not need all this hose assembly..? If so this may be better option.

Secondly: Sill plastic covers were glued on with a LOT of black mastic, is this normal, or did the previous owner do this? Should I do the same when putting it back?

Thirdly: I reconditioned all the rear end brake bits (callipers stripped and painted, new discs, flexi and fixed hoses, splash covers galvanised etc), I put new ABS cables in as well, as I may have damaged the originals taking them out of the rusted hub. ABS light will NOT go off!! I've tried replacing one side with the old cable (only have one usable now), and the other side, and taking for a spin in between, and no luck (apparently the system resets if you drive >5mph?). I've also checked that each side gets a signal from the CPU, and it blips every couple of seconds, so all good. They are after-market cables, but I wouldn't have thought they would cause me this much grief!!!

Any ideas or comments welcome to 1, 2 or 3...