Dumb question, but why did you have to remove your keyboard to install the ACA card? Shouldn't it have just slotted in from the bottom?
I'd re-check all your connections and your installation, especially check that nothing on the keyboard is coming in contact with anything on the motherboard (maybe related to your second issue). The ribbon on the A1200 keyboard can be repaired in various ways, but IMHO this is a huge pain-in-the-a**.
You don't say where you're located, but AmigaKit has new A1200 keyboards in-stock for under $40, just getting a new one to test might be your easiest option. Good luck!
http://amigakit.leamancomputing.com/catalog/product_info.php?products_id=336
