Of covering any type of floor with felt prior to trowling on mortar and setting tile. It would seem to me the tile would be floating on the thin layer of felt rather than being bonded to the floor. Not a good situation.The latex modified thinset mortar you are planning to use is a good choice. I have always had good results with TEC 345, but I am sure there are other good brands out there.
Good Luck!
Dodgeman