Bill, here are some suggestions for the "new to you" bike.
1. You're right, the oil/filter should be done.
2. Also, check the condition of your tires. Check for cracked sidewalls. If you have a lot of cracking, you might want to replace them.
3. I don't think you have to worry about your brake fluid right away but it doesn't hurt to flush the fluid. If you do it yourself, just make sure you don't get any fluid on your paint (brake fluid will ruin paint).
4. Run some Seafoam through your carbs to help free up any gumming that might have taken place.
5. Check your battery connections to see if they are loose.
6. Check the vacuum connectors on the carbs along with the intake rubbers for deterioration.
7. Popping could be coming from the Air Injection if it is still hooked up. That will also cause your pipes to turn blue. Suggest removing it and installing plugs.
Oh, btw, all these suggestions can be done by yourself with relative ease. There is a ton of info here and on Dinqua's site to help.
