Heh, after 6 years, most quirks are learned responses that you have "accidentally" taught him.
1. A vaccum works
1b. I think that should be safe, but if you are worried about it, look it up here:
http://www.aspca.org/pet-care/animal-po ... xic-plants2. Hmm, now that's kind of interesting. I would say that although your mother is doting on him, he isn't digging what she is doing necessarily. Tell her to bring some treats that he likes particularly well when she comes, that will help grease the wheels a lot!
3. Learned behavior, and a funny one
4. You can only hope it's lifelong, as that would be a sign of good health and happiness
5. It doesn't hurt if you do it right, but it's not a pleasant experience either. He's just letting you know in case you didn't remember that from the last lesson. Also, you really have to ask yourself whether what you are doing is worth the stress and unhappiness it is causing him.
Sounds like a really nice kitty that is well integrated into the fabric of your home and daily life. Awesomeness!