You don't need to lube the ball links. There is a tool called a ball link sizer and is normally around $5 and you use that to make the hole bigger in the link, so it moves easier. You can also fly with it like that and the link will size itself over time.

I wouldn't recommend WD-40 on the mainshaft. It will probably collect dust and dirt and make it hard for the parts to move up and down easily. Tri-Flow works pretty good and doesn't collect dust. You could also use a polisher from time to time. That would probably be the best way to go. I just don't put anything on the shafts.

You are correct that CA is for metal to plastic. I don't normally put CA on screws going into plastic unless it is a part that is hard to check if it is tight.

Nick