Mid-2012 Macbook air wifi connectivity, bluetooth interference, and SD slot

I've had issues with all off these things since right around the time my warranty expired:

-Wifi is often slower than all other computers in my house no matter where it is; it doesn't work at all if i have bluetooth on and connected to something. this seems to be a known bug that apple won't acknowledge- there are discussions of it here and on macrumors forums

-The SD card slot often ejects or unmounts the storage expansion that I keep in it full time. not just when battery is low or even while sleeping, but sometimes while I am sitting at the computer working. I've had to repair the sd card with disk utility multiple times as a result.

-Battery life is down to about 3 hours- battery health says it is at 83% of its original full capacity but I know it used to get 6 hours easily, and mavericks was supposed to improve that. I'm wondering in part if the SD card is part of what's killing it, but there is no way I can find to really get a deeper analysis of what's using the power. I do nothing on my computer except use office applications, browse the web and listen to music through headphones or a wired speaker (since BT won't work with the internet).

Mid-2012 13" MBA, running 10.9.4. I have no pirated software on here and have been gradually moving things to cloud storage, so the hd is only 54% full. I'm going to have to pay for a support ticket to get any help on these things, so i'm wondering: Is it worth it? Will I end up paying for every separate issue? I feel pretty confident Apple support is not going to acknowledge the first two points are part of larger and unacknowledged issues, especially being out of warranty, and battery life is so subjective.

I'm honestly feeling close to buying a windows 8 machine.