Hi Sunny315. Welcome to the boards. As an FYI, you should probably post your questions as separate threads in the "Problems" forum, instead of at the tail end of this thread, you will get a better response. I'll answer it now since it is here, and before you catch hell.
Your steering wheel shake is most likely caused by a warped front brake rotor. If the steering wheel shook during normal driving (without the brakes being applied) you would be looking at wheels that need balancing, out of round or flat spotted tires, or possibly bad front wheel alignment. But a steering wheel shake during braking is a sure sign of a warped front rotor. You can have it fixed by having the rotors resurfaced (hopefully the rotors are within tolerances to be resurfaced).
As to the temperature gauge problem, that is a little tougher to pin down. Could be a defective temp gauge, defective temperature sensor sending unit, blown fuse, wiring problem, etc.
Good luck.