Yes those links work, thank you. I wasn't familiar with what github was or navigating it, I've taken some time to become more familiar with it.
Thank you everyone for your responses. I'm going to sit down and take a good while to really read through as much as I can on these forums and through the documentation before I ask anything else, though I do still welcome any advice regarding hooking it up to GM HEI- I haven't found too much relevant there. I may try my hand at soldering up the board but looking through the prices of things the completed board is a very reasonable price.
Once everything is in my hands and I get some time off work to swap in the parts, I'll post build progress on hooking everything into speeduino.