The first thing I would check is to make sure that the lugs nuts are all on tight. Another thing that could have happened is that someone could have knocked a weight or two off of one of the wheels causing it to be unbalanced. If this is so then the tires will need to be rebalanced. Good luck.
Get you front end aligned, that should take care of the shakes.
Depends on 2 things, Do they shake when you step on the brakes or are there grooves in your rotors? If you answer yes to either of those 2 questions I would say yes
If you do not expect to stop the vehicle, then yes. Your front brakes provide up to 80% of the stopping power of your braking system. Without them, you would NEVER be able to stop your vehicle in anything resembling a safe amount of time. PERIOD! Not to mention, you would probably be replacing your rear brakes every week if you managed to put enough pressure against them to stop your vehicle at all - AND you would ruin your calipers on the front from not having the pads in place to keep them from hyperextending - which would also cause brake fluid loss, which would keep your rear brakes from working.... So, bad idea. Do *NOT* EVER drive a vehicle that has no working front brakes. Need I say more?
prob a broken belt in one of the front tires
Normally this is caused by warped brake rotors.
The cost for the front and back brakes would be about $600 dollars.
A common reason is that the front rotors have warped. Go check out WikiAnswers on the topic of "warped brake rotors". Rotors should wear out smoothly in normal driving. Use of the brakes that generate lots of heat (hard braking, riding the brakes) will result in warped rotors.
Bleed the master cylinder.& then rebleed the system.
Unbalanced front wheel.
There wouldn't be.
There are a number of things that I know of that can cause this one. First off did you have an alignment done after replacing the tires? I would also suggest checking out your front end ie ball joints, tie rod ends, wheel bearings and so on. Good luck
How to fix brake will not bleed out