Few questions....

Has anyone stained a concrete floor after removing tile? If so, how much work (as opposed to doing on floor after carpet removal)did it take to prepare floor?

I've read the main thing to do would be to sand the floor. How DIY friendly is this?

The tile and thinset has been removed, although there are places you can see where thinset was applied. Should this not be a DIY project, what kind of cost am I looking at the contract this out (about 350sq feet)?

Last question. If you had tile, removed it and stained the floor....how did it turn out?

If you try to stain over the concrete the grout lines will probably "ghost" through. You will probably need to overlay/ micro-top to prevent this.

Yea, the more I look into this it looks like the "ghosting" will prevail.

I going to go ahead and clean the floor with the appropriate cleaner and buffer machine. Maybe try a sample dye (talked to a pro yesterday-this seems better than an acid stain) behind the fridge.

Anyway, should we need to lay an additional overlay...how difficult is this? I know it will take a little trowel work, but are the various overlays somewhat self leveling? In other words, would it be hard to screw up?

If you overlay, watch the so called "self leveling" overlays. Any/ all products, on the market, take a lot of work to get smooth/ flat.