how hard to install upper and lower control arms?

You will need a half-inch drive breaker bar, a floor jack, two jack stands, a good set of both standard and metric sockets, as well as combo wrenches. It took my friend and I about two hours working in my garrage. That was from the time we removed the wheels to the time we put them back on and lowered the car. It is pretty easy.
 
Depends on the brand. I bought some cheapos on ebay for my wifes GT, they were a PITA. Took all day.

I bought some Granatelli upper and lowers for my Cobra, sliped right on. No hassle at all. Just some fancy work with the jack.

The breaker bar is a must. The bolts on the lowers are usually bent a little, so they need some convincing.

Deffinatly worth the install though. You will feel the difference. LT
 
Yep worth the trouble, mine took 5 hours total, with two bolts taking 4 of those hours. No crap, lower rear bolts where siezed to the spacer/liner thing inside the arm would turn and turn..lol, finally took the brakes off the car and beat them out with a sledge and a piece of rebar. fun. working by myself. woohoo.