Preventing and Cleaning Toilet Rings?
Use a pumice stone (similar to the ones women use for feet) they have them made for cleaning purposes. They work great but you have to make sure the toilet surface and stone are wet before you use or you will scratch the bowl.
Getting Vaseline Off a Couch?
Try dish soap.
Preventing Mold In Toilet?
Use clorox bleach toilet tablets (ones you put in back of toilet).