1. Ask teleflex, but someone in here might know.
2. "Loom tube" is probably what you;re asking about. Black usually, split tube that u feed lines/cables into, can get around the 50mm size at joints like whitworths/bias etc.
3. Measuring it properly is probably the most important thing. You need to be accurate and there is a proper way of doing it that teleflex advises. Look for a youtube vids using teleflex installation type keywords and might get lucky or ring them. Not advisable to just estimate accurately or get the next size up if unsure.
4. Just follow their installation and shouldnt strike troubles, esp if u measured right. See if u need to change the route of a new cable first, i.e. still have easy access all the way.
hope that helps...not a pro but have helped install a cpl.
Hopefully someone who has done it for a living will yell out to help. Just keeping your thread bumped near top on page 1 with some amateur hour stuff for best chance of pro help. Plus i;m bored shytless and its pissing down.
Steve