I get most my random pieces from ebay... has not let me down so far...
As for the screen protector, I believe these are "fused" together with the display and the digitizer... They use some type of silicon glue, you will need to heat it up and slowly pry around the edges to separate it. A hair dryer will work but, you're probably better off buying a heatgun.
The only apple product I have dealt with was an old Ipod touch where I replaced the digitizer. I have also done the same thing on many phones as well as random things like fixing connections, replacing bluetooth, wifi, etc...
Nothing too hard, my biggest tip is to use something soft plastic when separating the case. I used a credit card the first few times and actually messed a few clips up.
