Does everything fit in the slots where you didn't have to force it?
Computer parts are designed such that they won't fit in the wrong way. Just make sure the little triangle on the CPU matches up with the one on the board, and that it has a good connection with the heatsink. I bought a new heatsink once that didn't even touch the processor

worthless.
Now on the RAM, I can't tell how you've got it setup, but with dual-channel you want to try and keep identical sticks (same speed/size) in each channels (which is why you by in packs of 2 or 4). If you only have 2 sticks, make sure they are both in the first channel, looks like yellow would be the one.
For the USB thing, maybe this'll help: