1996 Chrysler Cirrus Car squeals, steering choppy, heat col

I don't know if this is one problem or many, but my car is giving me serious troubles. To give some history, I bought the car about 5 months ago used from a dealership in a nearby town. The car was almost perfect, ran beautifully, smooth ride, great start, etc. It hadn't given me a problem until about 2 months in, when my water pump went.

I got the water pump replaced and it's been okay, save one time where the coolant leaked completely. It hasn't happened since, and I'm not sure what caused that. I just got my brakes done, and they're fine.

However, my car, as of late, has been giving me a lot of troubles. When I start my car, what seems to be a belt [though I'm not sure which one] squeals for several minutes as I'm letting the car warm up.

When I turn my wheel, the steering is choppy, as if it's fighting me. It feels like someone has got hold of it, and every few seconds, grabs harder. Its hard to steer in the first place, but it's like a pulsation I guess. My heat comes out cold 70% of the time, and my car has been overheating often.

I'm really worried about these problems, and I"m worried that perhaps the mechanic may have done something wrong. I was told that whenever a timing belt is taken off, it should be replaced, but during the water pump job, they just put the old one on, and when I went to pick it up, they put it on wrong, and my car rocked violently. They fixed this for free, but I'm still worried.

This is my first car, and I'm not sure what's happening. Someone please help?

Thank you in advance