The oil in the coolant is most likely not oil. Since oil does not pass thru the head gasket with any pressure there is little chance of oil passing into the coolant system. The original coolant was a orange color. As that coolant ages it becomes a brown slim commonly mistaken for oil. It will really slime up your overflow.

Condensation on the oil cap is very comon on cars that takes a lot of short trips. That by itself is not a big deal. So neither of your syptoms mean much but that does not mean you do not have a problem. I would pressure test the coolant system to be on the safe side since you saw smoke and you are getting the random missfire. You can borrow a pressure tester from autozone and search youtube for coolant pressure test. Its pretty easy to do.

Random missfire is a pain to figure out. Is your husban thinking about doing the work himself? If the plugs and wires are not new that would be the first step.

 

I forgot all about the machine shop prices. If you do the job yourself make sure to get a torque angler. You cant really eyeball it in that tight space.

 

It would definitely be hair pulling irritating if you did all that work only to have it happen again and find out you have a warped head. I hope you got a good deal on your car.