Photoshop CS4 (and most other CS4 apps) benefit from having a nice graphics card. However, it isn't a requirement.
As for your motherboard, you can probably settle for the ASUS P7P55D or P7P55D LE. If you want the newer ones with USB 3.0 and SATA 6Gbps, they are named the P7P55D-E series. The base "P7P55D-E" might be the one for you.
On the other front, the GA-P55-UD3 is a good matchup for the rest of your system.
The 380W PSU is sufficient, yes. But you might want to go up a little more, to be on the safe side. Try a 500W PSU instead.
As for the RAM, any reputable vendor like Kingston, G. Skill, OCZ, Corsair, and many others should be OK. If you will not overclock, DDR3-1333 is for you. You can also opt for DDR3-1600 modules, but you must oblige to overclock your CPU to run the RAM at 1600 MHz. This should be too much of a problem. The i5-750 is perfectly capable of running at 3.2 GHz.