Need Themostat could not having any antifreeze in your car cause your car to stall out and lock up (brake & steering wheel) - I am aware that I need a themostat put in but in the meantime, I have been making sure I have a good amount of antifreeze in the system. Just recently, the needle has not been going past the halfway point (from cold to hot) so I have not been getting any indication that the car is close to overheating (like it has a few times in the past) - Today was the first day it finally stalled out a couple of times (and had a hard time starting back up) --- could this be because there is no antifreeze in the system? or something worse?

If there's no pressure on your brake pedal it's due to a failure somewhere in the braking system. I can't see any connection between a steering problem and a braking problem.

Most cars have a split-circuit braking system. That is, the front left wheel is on the same line as the rear right wheel. The front right wheel is on the same line as the rear left wheel.

This is just a safety feature: If one brake line loses pressure, the other line still works and you retain 50% of your braking power.

check the level of your brake fluid. If the level has dropped it indicates a leak somewhere. Though be aware that it is possible NOT to lose brake fluid whilst having soft brakes..

Brake pressure is lost due to either a faulty brake master cylinder or a leak at one of the wheels.

Remove each tyre in turn and inspect the piston on the brake calliper. If there's slight wetness caused by brake fluid that indicates a seal (around the brake piston) has failed and is drawing in air.

There's no need to replace a calliper - overhaul kits are available.

The link below shows generic images of brake calliper pistons/seals:
brake calliper piston Google Search

More than likely a vacuum leak. The steering is not really locking, that would be your power steeing not working because the engine is quiting.
Look for a vacuum leak.

APPLY BRAKE AND MAKE SURE STEERING WHEEL IS CENTERED. IF IT IS PARKED SO THERE IS PRESSURE ON THE FRONT WHEELS AND HOLDING THE STEERING WHEEL HARD RIGHT OR LEFT IT WILL MAKE THE KEY VERY HARD TO TURN.

It sounds like the steering lock has gone hard due to turning the wheel after key is out, turn the key and steering wheel at the same time and see if this releases the lock. Hope this helps

Was the steering wheel locked, or just stiff to turn?
I imagine what may have happened is that the engine stalled while on the move. This would effectively kill vacuum brake assistance, and stop the power steering pump at the same time, causing very heavy steering.
You will need to check the condition of your engine components if this was the case. You can start by checking the condition of the following:

1) Spark plugs, leads and coil(s)
2) Air filter
3) Fuel filter
4) Idle control valve

on any vehicle with power/power assisted steering and brakes the power assist is created by vacuum that the running motor generates on the intake manifold so hard brakes and steering are normal and dangerous when motor stalls. Now the question is : why does your vehicle stall? I need more information to help you on this. Check air/ fuel filters and for pressure on fuel rail first, then we go from there...

Your are correct. The steering has nothing to do with the transmission. It is not a good idea to use the power steering to turn the wheel lock to lock on a hard surface, and especially not with the brakes on. Howerver, if you do this, and the car is in drive, you will be putting more load on the engine and cause it to lug down at idle, even more. It is possible to actually "stall" the toeque converter with out harming it. In fact this is one way of testing for slippage in the transmission clutches and brake bands So the answer to your question is no..

Sounds like the main cause is the engine is stalling. This will cause the steering and brake problem which is what you are probably noticing first while you are driving. Now the question is why is the engine stalling. The list of possibilities is great and would take some diagnosis to figure out. If you know how to repair cars then check the fuel and ignition system and have the computer scanned for any codes. If not then take it in and have this problem checked immediatly. Loss of steering and brake control is dangerous and should not be take lightly! Good luck!

To begin, are you parked on a grade or with the front tires against a curb? The steering wheel lock is mechanical; a metal pin or plate engages a notch in the lock plate which is under the steering wheel. If there is rotational force against the lock, such as by a front wheel being "pinched" against something, the force against the lock tang makes it very difficult to retract it by only turning the key(I've seen people break the key off trying to force it to turn). The best, most simple thing you can is to grab the steering wheel and use force to rotate it while trying to turn the key. If this doesn't work or if you don't have the strength, try getting a friend to: #1 block the rear wheels so the car can't roll, and #2 jack the side where the tire is against something up to release the pressure. Then you should be able to turn the key. ps, be sure in the future to avoid having the tire against anything when parking.