No you need to buy Stabilia if you want qualify waterproof and dust proof
The battery is a rechargeable, replaceable Li-ion. It is proprietary through Milwaukee tools. I don't have the number.
Yes, and quite easily. The instructions are in the manual which is provided with the tool. But you can also access ALL Milwaukee manuals at their website under "support" then "manuals." That's true for EVERY tool they make! ;-) Hope that helps.
I just tried to stick it on my 24" magnetic level and this digital level will not stick to magnets, so, unfortunately, no.
currently not in the plans for a 12 volt level
This level will display degree, inch and mm...
I have not heard or read of any such plans