Is this '96 Protege with 88k miles worth fixing?

Hey everyone, I am extremely naive when it comes to cars so I just thought I would ask you all for some advice. I just purchased a 1996 Mazda Protege LX with 88k miles on it. It has some problems that I have noticed and I am unsure how to handle them. I observed that the temperature gauge fluctuates (Faulty thermostat?) up or down only when the AC or heat is not on. It idles kind of weird (EGR Valve issue?). The gas gauge does not work (sending unit?). The exhaust flex pipe broke while driving the other day now the car is extremely loud to drive. The valve cover gasket is leaking (maybe?). The steering wheel constantly jerks while driving (alignment issue?). When I put the car in park the RPM revs up past the "2" mark (idle issue?). I don't even know where to begin with fixing this. I bought it because of how low mileage it has but now I am second-guessing myself, is this car worth fixing all these things? What is an estimate of cost to fix all these things?
 
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