Since you are trying to do this right I would recommend a good unmodified thinset (dry-set) that you would add a modifier to. I like to use Mapei Kerabond thinset with Keralastic additive (milk).

You could use a modified type thinset, but mixing in Keralastic is superior.

I would use Laticrete Spectralock epoxy grout to resist stains and mold. There again... this may be overkill, but it's not that many sq ft here.

If there are no cracks in the slab you can just go right over it. If you want you, you can install Ditra membrane but that will mess you up on the modified thinset I recommended.

Jerry:

Thank you very much for your input.

I called a tile company yesterday after I posted my message and was told to use the the exact same thinset that you suggest and the same additive as well - fantastic. I will also look into the grout that you recommend.

The concrete slab is fairly new - no cracks, so I will go right over it with the thinset that you suggest.

Much appreciated.

Take care.