Don't worry man, I know the feeling. One broken thing is one thing, but four or five and it gets expensive quick. I've been their. It sucks.
The expansion tank will need to be replaced. If you didn't overheat the car you should be fine. As long as theirs no visible leaks then you should be okay to hold off on the coolig system. Check the oil to make sure it's not milky brown. That indicates a head gasket leak.
As for the power steering pump start with the belt. If you have a floor jack and jack stands you can probably fix and diagnose it yourself. Replace the belt and the fluid and with the car on the Jackstands turn the wheel to make sure the fluid gets through the lines and see if their is any issues. It should turn smoothly with little resistance.
Make sure you tell him ahead of time your on a budget and you only want certain things replaced. Clarify that only the parts YOU specify are to be replaced. Put in writing if you have too but your not obligate to pay for anything that you didn't want and any honest mechanic would meet try to push repairs that are not needed. I ALWAYS look at the parts he is recommending that need replaced and have him explain and show what is wrong and why it failed. A good mechanic will take te time to explain it to you. If they don't want to or refuse take your business elsewhere.