1. No, even if you truncate the release samples at rank loading/routing time, there is some reverb from the room recorded during the sample loops unless the sample set is explicitly dry.
2. Noise samples are usually on the rank loading/routing window so you can choose not to load them.
3. I don't recognize this situation, after using MIDI learn today to set up about 60 stops and 50 pistons. I've done this for two dozen sample sets without finding any bugs in the process, including remapping MIDI controls where my existing master combinations were preserved with no effort on my part. Perhaps you could explain what you're trying to do step by step and say where it seems to go wrong.