Hmmm, a little chemistry goes a long way here...
The "Klear" stuff is simply water with some detergents, so it should not attack paint in any way. (Imagine your floor if it did...) Softening water is a semi-jargon term and has little to do with actual softening of anything touchable.
"Oven mate" is alkali-based and therefore attacks paint and many organic substances, skin among them (but not plastic in minis), but may also corrode metal. Whether it does depends on the composition of the mini metal, but it is a possibility. I would avoid using it simply for its aggressiveness and possible injuries (a little splash can damage your eye permanently).
What you call "acetone 2-propanone" is in fact samply acetone; "2-propanone" is its chemical name.

Yes, it does literally dissolve paint. I doubt you will find any of it in nail polish remover, for this is ethyl acetate-based nowadays - but that works as well. The easiest and cheapest source would probably be do-it-yourself shops; acetone can be bought as industrial solvent (for e.g. polyurethane resins), while ethyl acetate is a widely-used paint thinner (there are generally two types of these, one is benzin-based and smells like naphtha, i.e. sweetly, the other is ethyl acetate and smells... like nail polish remover). Ah, and acetone does not burn your skin; it simply over-dries it, which itches, but is not really harmful.
Brake fluid seems to be the most universal agent, though, as it works on both enamels and acrylics and does not corrode plastic or metals.