Porcelain Tile in my Garage

[johnr9q]

I have been researching this for days and need some help. My garage has a concrete floor. I live in Sacramento (a Mediterranean climate) I ground my floor with a 70 grit grinder to get the epoxy applied 22 years ago and I now have a smooth and level surface with no cracks. I had the expansion joints mudded over during pouring. I used a 5 sack mix with rebar and 5 inch thick. after research I want porcelain tile with a PCI of 4 or 5 and slip rating of R11 to R13. I have gone to most of the tile stores in Sacramento and can't find anyone that is very knowledgeable. I am not sure if I want 12" x 12" or 12" x 24" (seems like most tile is now in a 12 X 24 format) (Home Depot has a 12 X 12 tile that is PCI 4 and cost $1.50 per sq ft which sounds pretty good) I am not sure if I want to look for or even how to identify tiles that have the following Charteristics (which, after research, I think I should be looking for) Color all the way thru? I recently discovered that the PEI rating only refers to the surface scratch resistance (Earlier I thot it referred to the structural integrity of the tile, will it break under weight) Is there a way to find out if a tile will hold up under weight or are all porcelain tiles rated for heavy loads? Do I need vitrified tiles? Do I need Rectified tiles? Do I want glazed, unglazed or unglazed that is polished tiles? Should I use level master to insure tiles are all level with each other? Should I use Red Guard or equal for a primer? Should I use Schluter Ditra to reduce cracking under movement? What should be my grout space be? I read posts from "Dakota" that sound like he works in a tile store and is an expert. How can I find someone like him to give me answers?