There are various options and there are some speciality tints too. Rustoleum Rocksolid has some good options There are 3 colors of pretinted: grey, mocha, and tan http://www.menards.com/main/p-2765847.htm?cm_vc=PDPZ1 http://www.menards.com/main/search.html?search=rocksolid+garage Otherwise there are lots of other tints that you can add to a clear base. This link is the kit for obsidian. http://www.menards.com/main/p-2765821-c-8022.htm?tid=1602039543339560932 Other tints http://www.menards.com/main/search.html?search=rocksolid+tint

It depends on many factors. I prefer to do what we call a bonded mud screed or "dry pack" floor most of the time, other times self leveling can work but from what you've mentioned i don't think so. You have to thick of a pour for most all self levelers. and they are tempernmental in cold climates over crete. Share some pics, condition of the slab?

I spent about 6 hours removing 15 lineal feet of 5" wide wood floor that had been glued down properly. Yes, I had to be more careful than you because I was doing repairs, but I would seriously consider going over the floor instead of removing it. Sophie's advice is excellent as usual, but you may need some marijuana after the pizza and beer.

Or the cheapest solution of all: ignore the unevenness, drop down a vapour barrier such as 6mil poly sheeting and then lay the vinyl. Since your budget is so tight that $100 worth of testing is pushing to the brink, you might as well purchase the cheapest vinyl product and lose the warranty (as in ignore the flatness ratings). Put down the vinyl and hope for the best. No. I'm not kidding. Simply install the vinyl to the best of your capabilities (use the vapour barrier for $0.11/sf includes the Red Duct Tape you need) and leave it be what it is. You will spend more time and energy (and money) trying to figure out the work around when there really isn't one. You either spend money on the test or you spend money on the subfloor system like a sleeper system (more than $100) or a DIY option like Dricor (really not $100!!!). Or you ignore everything and lay the floor over what you have. Those are your options.