Electrical nightmare!!!

check all your grounds as well as making sure that you hooked things up right.

Replacing harnesses on these cars is not always the answer. THe wiring can be high maintenance, but it's also a pretty simple system. You need to get a decent test light and start working one problem at a time. I would start with the brake lights since that's the easiest to troubleshoot. And if the fault in the brake lights leads to the turn signal switch, it may clear up the other problems when replaced (if thats the problem).
On the brake pedel there is a contact switch with two wires to it. THere should be 12v on one of the wires all the time. CHeck that first. When you push the brake pedel, the switch should close and send 12v out the other wire. Make sure it does that. That 12v goes up to the turn signal switch, through the switch and back down TWO wires-one to the left turn signal/brake lamp, and the other to the right turn signal/brake lamp.
With the brake pedel pushed you should have 12v at the socket in the trunk on the Green w orang strip wire (left) and the Orange w/blue strip wire (right)

Check that and post back. Worry about the turn signals later. And we do want to know if the connection at the steering column harness has been butchered up. Tere should not be any cut or spliced wires at that connector.