I plan on using a product call Dri-core and then carpet/laminate over it depending on the area. Its a nice product that should help you level out the uneveness of your floor, it also sits up on plastic bumps which keeps an air gap from the concrete which will help with any moisture and keep the floor warmer.

Here is a link that might be useful: Dricore Website

HI - please note that MOST concrete floors (especially in basements) are far from level, are bumpy, etc. But none of this should preclude the use of tile. THere is a somewhat expensive, but very good product called Level Best. I have used it twice with great results. Basically it is mixed with water to a near water-like consistency, and dumped on the floor. Being like water, it quickly finds its own level, & hardens (within minutes) to a rock-like hardness, perfect for adhering tile. I would first put a hydraulic cement on the crack that you found, & go over it with the leveler. Also, another suggestion: consider heating the floor UNDER the tiles (www.thermosoft.com) A big complaint about basement tiles is that they are COLD - especially a bathroom area. I tiled my last house & it was very cold in the bath. IN my present house, I'm in process of installing radiant floor heating under the tile. It will make them warm & comfortable.

I found a product that would cover your floors imperfections. I really liked the way it looked on the display at the store. They used masking tape to simulate grout lines and then applied the coating. When removed it looked like cobblestone, and was beautiful. The product is advertized for indoor and outdoor use. It is made in two different forms. One is called Spread Rock, and the other is called Spread Stone. You may see pictures on line at www.daichcoatings.com. I was really impressed with it.

the spreadstone looks very interesting. Has anyone used it before?

I'm thinking of installing hot water radiant heating under slate tile in my basement. I'm looking at using a radiant foam tarp called Insultarp in place of the usual thick rigid foam. My concern is keeping the total floor depth to a minimum to maintain my limited headroom. I need to know minimum slab thickness for embedding 1/2 inch PEX tubing.
Anyone have any experience with any of this?