I just finished an ez wire kit in a 1940 Ford pickup. This was my first "Kit" I usually do them old school with spools of wire. This one was a kit that the owner already had. I must say the kit was easier. Especially with every wire marked it made hooking up a lot easier and I would suspect troubleshooting would be easier in the future if ever needed. I put about 15 hours in this kit total. I didn't feel that was too bad. I only worked on it a couple hours in the evening. I probably could have saved some time doing it all at once. So to answer your question, it really depends on how knowledgeable you are with wiring. If you have to have this truck for transportation, I would definatly say allow yourself a full weekend. But if you have no problems and if your old system comes out easy you might get done in one day. It is certainly not a couple hour job.
I have never used EZ powerwindow kits so can't comment about them, however, the wiper switch. No you will still have one speed on your motor. The difference will be you will have a switch setting that doesn't do anything. If you want two speed wipers then you need to install a two speed motor which will hook up to the other switch setting. Hope this makes sense and good luck