$300 Budget AMD rig

Hey everyone! This is my first post, and it's a bit of a doozy, so bear with me!

I am finally parting with my old P4 Prescott system. After many many years of faithful service I am finally upgrading.

I have an extremely tight budget, around $300-350 USD to spend, but considering what I'm coming from, I think I have enough to see a world of difference.

Of course I would love to go the i5-3570 / z77 route, but unfortunately almost my entire budget would be taken up by those two components.

My main goal is to build a rig that can play recent games at playable settings, but I would like to have a decent upgrade path. I already have an OS (Win8Pro), and a graphics card that will get me by (HD6670 gddr5 1gb) until I can afford a nice one. Here are the two processors that I've narrowed my search down to: A10-5800k and FX-6300.

Here are a few questions I'd like to hear from you all about:

1- Are there any processors that I should also be thinking about? I've checked out the Phenoms and i3's, but there may be something I am missing.

2- Since I already have an HD6670, would going the A10 route be better for gaming? I would be sacrificing almost all the CPU cache to have the ability to hybrid CFX the APU's gpu with my 6670, but I've heard mixed reports about hybrid crossfire.

3- Would going the FX route give me more in terms of upgradeability in the future? I've heard that AMD plans on sticking with the AM3+ for a while, and I would doubt AMD plans to stick with FM2 long term. (EDIT: After further review it does appear that the FM2 will be around for the next APU line)

4- Is it worth spending a little more for 1866 ram than 1600? I would think this is a yes if I was to go the APU route, but I'm no expert on this.

5- I am not opposed to spending $100 for an a4-3400 and a cheap FM1 mobo if in the long run I'd be better served to save for the i5 system, but I am definitely feeling the effects of a single core CPU in a multi-core world. Is this a terrible idea?

Thanks!
Edited by storox - 10/31/12 at 7:05am

Thanks for the replies! I have been reading about HSA, and I'm really interested. This is somewhat off topic, but it seems that the APU line will be taking advantage of HSA, and thus the Steamroller upgrade might be the most viable option for me. However, with gaming being the most demanding thing performance wise from my system, can anyone explain if/how HSA will affect gaming performance? I am leaning towards the A10 for it's cost/benefit advantage, but I'm still undecided.

My monitor is an ASUS VH242H, so native is 1920x1080. I realize that neither the FX w/ 6670 or the A10 in DG mode will deliver a smooth gaming experience at those resolutions. Coming from a P4, I'm more than used to playing games at 1280x720, so that is somewhat my target resolution.

Thanks for your advice on the parts! That setup is actually really close to what I was looking at, although correct me if I'm wrong, but the A55 chipset is the base chipset, I was hoping to find something with the A85, as I don't really want to have to upgrade mobos when Steamroller comes out.

I'm also looking into OCing the CPU and GPU of the A10, so if anyone has any information on how OCing an IGP and Discrete works, feel free to tell me. I know, I have a lot of questions, I've been out of the PC hardware scene for a few years...
Edited by storox - 10/31/12 at 1:38pm