1. Good to know! I hadn't noticed the double feature yet but that helps a lot. Makes this feature request at least unneeded for 2 of my games
2. I've encountered similarly odd values in several apps so far so I think it would be a universal feature. Some apps multiply the values by 2, others by 10, etc... I think it's fairly common actually.
3. Naturally it should be an add as you need type of thing. If you add 10 values you'll have 10 values available (although loading/saving maps from/to files could be useful).
Distributing a few "standard" (2 times, 10 times, etc.) map files might be useful in that case. But even that's is just a nice to have initially.