Help is my car going to shit?
 

Just bought the car a few days ago and everything was fine at first. Just today I pulled out of a stop and now when I'm cruising I hear there is a constant knocking or banging sound coming from the rear only when in gear and there is some slight shaking at idle. Watching the tachometer it's just above 1k occasionally revs up a little maybe around 1.1k or 1.2k. Is that normal? When I'm on a fairly steep hill about 35 degrees or more the e brakes doesn't hold.

I suspect some teeth broke in the diff, e brakes are worn, and engine mount and/or apex seals are bad.

Can anyone confirm?

edit: Sorry. Over exaggerated title. I just want to confirm my troubleshooting as I'm new to vehicle maintenance and didn't want to blow a load of money on engine and diff rebuilds and unnecessary replacement parts.

Those seem like pretty basic mount, tune up, and brake issues. In addition to describing your problem information about your car is also necessary for more tenured members to blindly troubleshoot.

If you look through the FAQ stickies in generation specific forums you will find a lot of information.

I'm with Molotovman, likely your rear end banging issue is a broken diff mount and the other things are basic tune-up items.

Take a deep breath, don't jump to the A word right away :)