I would recommend the John bridge forum or floorstransformed.com
They both have very good information.
One correction though,
If you intend to go over the formica, you should not screw backer board down. just rough up the surface with heavy grit sand paper, and use a good modified thinset mortar.
Putting screws through the formica MAY
allow moisture to get to the underlying partical board, which can swell and ruin the tile job. You should only try to go over formica counters that are in very good condition, no cracks or missing pieces for the same reason.
And Porcelain is OK depending on the type, I have porcelain floor tile and it don't get scratched.