The LBS that I like the most charges a LOT to install fenders (relative to their other labor charges; maybe it's like $30). I think it reflects not the difficulty, 'cause they're pretty straightforward, but the *frustration* of lining up all the stays and making sure nothing impinges on the wheel or brakes anywhere. We have 3 bikes, I paid to get fenders installed on one, did the other 2 myself, and I can't really say I was freed from that much frustration on the one I paid for because everything rattled loose eventually.

One word of advice, make sure your bolts go all the way through the eyelets, like come out the other side. These will be rattling loose over time, so it's better to have as much thread contact as you possibly can get. For the 2nd bike I put fenders on, I decided to go get new bolts long enough to go through first the fender stays then the rack and finally all the way through the eyelets. I think that's mostly an issue because during the course of rattling free from normal road vibration, the threads can get damaged, so it could get progressively harder to re-tighten it all back down. Maybe that's just paranoia on my part.

Pedals are easy. You just need an adjustable wrench to remove your old ones. For safety's sake it is best to put a couple turns on the new pedals with a wrench but you don't need to put a lot of your weight on it though, just make it snug, pedalling will take care of the rest.