RE: How much CA?
I just use what I feel is appropriate. On my 1/5 Scale Cub Build I have gone almost entirely through a 4 oz bottle of Medium Super Jet. The build is almost done and everything has been glued twice. Once to tack it and one to really bond it together. I wouldn't fear extra weight, there is just not that much glue there.
A sample of my project.....
SunDevilPilot