If you have no idea whether the driveline fluids, power steering fluid, brake fluid, and coolant have ever been changed, by all means do so when it is financially convenient for you.The general information thread
answers many of your questions. It has links to DIY guides and some other useful information, such as performing a full transmission fluid exchange in your driveway.
I think you should not need a mechanic or dealership to do any of the services for you except possibly a coolant flush, and brake flush if you have never done one before.
Welcome to NICO!