help me with my motherboard problem

[Gearstack]

I want to show you my PC specs first

processor: Athlon II X4 620
motherboard: gigabyte GA-MA785GH-US2H
RAM: 2x2GB DDR2
GPU: radeon HD 5870
PSU: corsair HX620w

I want to buy Gigabyte GA-78LMT-S2 and upgrade my processor into AMD FX6300. Due to certain budget I want to hold my processor into upgrading.
It says from their site that it supports AMD FX series as well as athlon II X series. I just want second opinion

for my first question: Can I put my old processor, athlon II X4 into the new gigabyte motherboard? and later on after I have additional funds I'll update it into FX6300. It says from their site that it supports AMD FX series as well as athlon II X4. I just want second opinion

second: can I still use my psu and videocard? I know that I also need to replace my ram into DDR3. speaking of ram's for my third question. what should I get 1333 or 1600?

lastly: what's the difference between Gigabyte GA-78LMT-S2 with Gigabyte GA-78LMT-S2P

Thanks in advance

 

[Ketchup]

According to Gigabyte, you should be good here:

CPU Model Core Name Stepping Wattage Since BIOS
Athlon II X4 620 Propus C2 95W F3

At first the F3 gave me pause, but it looks like this particular boards starts at F3.

I see no reason your original video card would not work here.