The pedals could be tough if you have to take off the old ones. It could take quite a bit of leverage if they've been on there a while and weren't greased when installed. If you feel like you're doing damage, take it to the LBS.

Just remember to move the wrench in the direction you would pedal to tighten, and the opposite direction to loosen. Make sure you clean all the threads so they're free of grit and apply lots of grease to the pedal threads before installing them. Do this with your rack and fender bolts too. It will get them nice and tight and keep them from seizing up if you want to loosen them later.

With the proper braze-ons on your frame the rack and fenders should be pretty easy. The fenders may be trickier to fit with caliper brakes.