[just another] Help me upgrade my rig.

Greetings. [I'm new here, obviously]  

I'm planning to upgrade my rig, as stated in title, and I think I might need help in doing so as not to end being frustrated with bad decisions in purchasing.

Here's my current setup:

Motherboard: Asus P8H67-V
Processor: Intel Core i5-2400 Sandy Bridge [stock cooler]
RAM: G.Skill Ripjaws 4x1Gb DDR3
Gfx Card: Sapphire Radeon HD5770 1gb
HDD: Wester Digital 320Gb + 500 Gb Caviar Blue
ODD: Samsung DVD RW
PSU: Enermax 625w 80+ (modular)
OS: Windows 7 32-bit

and things I plan to Upgrade and upgrade to:

RAM: add another 4GB
Gfx Card : Sapphire 6850 1gb
SSD: ???
CPU Cooler: ???

My reasons: (1)I'm adding another 4gb since I'll also be moving to a 64bit Win7 and I'll be slightly doing some video and photo editing, but the rig will most probably be for gaming. (2)Im playing on a 20inch monitor, and I don't plan to upgrade that in a year or so, so i went for the 6850. (3) My first SSD. (4) I'm not sure, but I'm thinking my CPU is hot sometimes, adding to the fact that I live in a tropical country and the temperature is really hot at times.

Questions: (1) Are these upgrades good enough? If not, could you suggest better ones, or I really don't need to?
(2) Do I also need to change my PSU to be able to meet the watt requirements? My PSU is a year old.

TIA and have a good day