Get a good gunsmith screwdriver set. Are you sure you can’t most of the rust up with a good CLP or Kroil and a rag? Doing that a couple times a week will minimize the amount left...unless you plan to refinish it.
The only time I ever took my single actions down was for action work or repair. Remove the grips, hose it down with brake kleen, follow up with Breakfree CLP. After that all you wil need is the CLP.
I just bought a used gun. It looks fine. However, I saw some very light orange spot. I think in order to find out what are hidden behind I need to completely disassemble it.
It's not that hard to re-assemble. Just lay the parts out on a towel in the order they come out. Remember to use a finishing nail to hold the mainspring in the compressed position.
While you have it apart, installing Wolff springs will greatly improve the trigger pull. Get the kit and install the lightest hammer spring. If you have ignition problems (You won't but stand by for the nay-sayers), you can easily swap out a heavier one.