Power line is cheaper and is a good option if you just need a better connection for something with an Ethernet port. Also do you need just a access point or a router? Or a router and modem?
I really like the Gigabyte UD3P, so I would recommend that, but it would still be more expensive it wouldn't be too different from your current builds price.
Yes, I know but it is still the same process but you just have to unsolder the two small pins. This video shows the pins and also shows how to unsolder them.
Well defending my position will make me sound like more of a fanboy but most people don't actually want to root and ROM a phone. I don't understand why but they don't. But still you don't need the extra RAM, there is almost no difference.
I can't recommend it though, the OnePlus One is only about 50$ more and feels a lot more premium. My friend sold his OPO to get a ZenPhone for the dual SIM feature but says he regrets it now.