Code requires 6x6 or
have your local inspector pass the 4x4's as they are so short, see the "notes" at the end of this Code Book: http://www.awc.org/Publications/DCA/DCA6/DCA6-09.pdf
Two bolts on each end of beams are required on a bearing post, notice the picture and placement Tables.
Concrete is a porous material that stores/wicks moisture and water like a sponge. Capillary action will wet the wood if drier than the porch concrete---- pressure treated or not, and soon start rot.The pressure treatment is against bugs and decay rot, not water. As said, treat the p.t. with a water-proof, the whole thing. I would use some Grace I&W shield on the side against the concrete and install it on stand-off washers for water drainage.
Screws are not acceptable other than on decking unless rated special as Simpson hangers/etc. Nails are called out on the Deck Code link stated. As are bolt placements, spans, piers, stairs, treads, risers, handrails, etc. It would answer any questions you may have though you need to read it first. Nice picture contrast and placement, BTW.