1. Not within PP, but outside of PP you could put only the needed clips into the folder for PP to find. The others would remain offline. This does require knowing in advance which clips will be used, though.
2. This happens every time you open a project. PP will ask for the location of any missing media.
3. This is a major flaw in the AVCHD design. You will have a hard time with this one, as there is no way to know which 0013.mts is being asked for. It's a big enough issue that you may want to seriously consider doing all the work one one machine.
4. No. PP doesn't create any reports.