This includes framing an item that is not acid-free. This will aid in the life extension of the painting. In the least it will prevent discoloration. Painting with plastic. Can be made to resemble oils, and work like them also.
Acrylics tend to have excellent lightfastness.
Either technically, or timewise, or both. You never know until you ask. Place where sales of commonly priced items are inflated by auction fever. Place where people market seemingly rare items only for you to find them on their website later, and usually cheaper. Resistance is futile, OPEC will always win.