A few sales questions

Okay, So I have a macbook 13in early 2014 1.4Ghz 4GB RAM and 128GB SSD. That's what all these questions are about.

#1 I have two Airport/Bluetooth cards. one came from eBay and one is the original that came with my macbook air. I cannot test Wifi on either because my logic board will not even detect the Wifi (issue on logic board end) on either while bluetooth works just fine on both. So would I get any sort of credit for sending iFixit one?

#2 Logic boards from iFixit are a tad bit to pricey for me. any reputable sources I could get one for cheaper?

#3 If I were to buy another logic board from somewhere other than iFixit, Could I still send iFixit my old logic board for the credit?

Some details about the Logic Board:

Has what I think is corrosion on the screw holes. I scraped it off about 2 weeks ago.

Water damage indicators show no water damage And neither do I remember spilling water on it.

A tad bit dusty.

Some details about the Original Airport/Bluetooth card:

screw hole has a little bit of corrosion on it. I scraped it off about 2 weeks ago.

extremely clean with no dust for some reason

Ebay bought card:

about the same. has marks around screw hole but doesn't look like corrosion/liquid damage.