Bal single part Flexible adhesive is what i would use. No need to prime but some fixers do. I would in this instance...belt and braces
When you say Concrete floor, is this a smooth floor or would it need levelling.
When some fixers (especially new fixers) hear the words Porcelain they tend to think of nightmare cutting. Its not always the case as Porcelain comes in different grades. Without trying to cut the tile you wont know how well it will cut. On the whole the most of the time i use Porcelain i have no problems. I use a Sigma cutter which allows me to snap the tile anywhere along the score line, i find that is the secret to a higher percentage of clean breaks. If needed i can use my Rubi DW250n for the wet cuts.