Not really sure what you mean by "tint and hue" and if you're using "MS paint" or "paint.net". Anyway, you might be able to find the RGB, CMYK or hexadecimal values usually used by graphics software using encycolorpedia.com

Be careful with that!  Computer monitors cannot reporduce the full gamut (they can't make all colors).  Plus, they can be pretty far off in how true the colors are - you'd be surprised when you put two monitors from different manufacturers next to each other and take a look.   

Depending on how serious you are about it, I'd say get a Pantone book.  I build a lot of prootypes for my job, and that's how we handle it.  We can take the printed samples aroudn in different light and hold them against different adjascent colors, then pick that way.  Then we mix the paint to match or sen dthe PMS code number to the outside source of end manufatcurer and have them match to that.  that's one of the beatuoes of it - standardized so no need to send samples and rely on interpretaiton and lighting to match it.  I've never done this with auto shops, but all other machine shops, injeciton molders, caster, finishing work shops, etc. all over the world can handlt it this way.  

At a minimum, I would recommend printing it out on a decent color printer with heavy, nice paper and checking that way once you ge tto something close.  Then you also have a swatch to take with you to whoever needs it.  

Between friends, there shoiuld be no secrets! ;)