Socket FM1 is for AMD's 1st generation APUs (CPU core + GPU core) known as Llano. Socket FM2 is for AMD's 2nd generation APUs called Trinity. It will also be used by the upcoming Richland APU later this year and the highly anticipated Kaveri APU that is supposed to be released in 2014 (maybe early 2015). Socket FM1 is dead and Llano APUs will not fit in socket FM2.
While the graphics core in the A8-5600k (HD 7640D ???) is the 2nd most powerful integrated graphics core, it and the A10-5800k's graphics core is relatively weak compared to a dedicated graphics card. The A10-5800k's graphics core (HD 7660D ??) is a little less powerful than a Radeon HD 6570. From a gaming perspective, the HD 6570 is not considered graphics card for games, it's more for multimedia.
Having said the above, at least the HD 7640D is more powerful than Intel's HD 4000. It can also be used to Crossfire with up to a Radeon HD 6670 for better performance as long as the game supports Crossfire. The Radoen HD 7670 is that same card as the Radeon HD 6670 with just a new name. It is also only sold to system builders like Dell. Not sure if it will be Crossfire compatible with any of AMD's Radeon HD 8xxx series card that are expected to be released mid-2013.
Intel's HD 4000 performance is actually pretty impressive considering that it is coming from Intel... meaning they never really bothered to attempt to design a graphics core capable of playing games. You can thank Apple for prodding them to develop the HD 3000 which itself was pretty impressive as well...