MOST important thing at this point is DO NOT RUN THE BIKE WITH THE FUEL THAT IS IN IT ....
remove the tank a.s.a.p., drain it, clean it using fresh fuel, and discard or run in your mower after filtering it out....
everytime you fire the bike up with that old contaminated fuel, you add another batch of stuff into the carbs that just compounds the process.
Forget the fuel additives, and clean the system well.
Procede to remove, clean, and flush all of the brake and clutch hydraulics. Use the recommended fluids, and do not get fancy. The bike is old school tech, and simple works.
Begin checking rubber parts, hoses, and hidden wiring for signs of critter gnawing or deteriation.
toss the tires, after they have sat that long they could fail.
do not be tempted to "spray wash" the bike, a gentle cleaning without high pressutre water works best. A leaf blower helps in the drying process.
Remove the battery, clean all the cable ends and terminals, and check electrolyte level, and then place on charge on the bench.
If you intend on running the bike for tuning and such, hook up a clean "remote gravity feed tank", like one from a small lawnmower, with fresh fuel. It insures you are not adding more work to your list...
Drain, clean/flush the cooling system, and replace the rad cap.
oh, Get the factory manual, and also the Clymers, they work in conjuction, and both contain information that compliment each other....
and lastly, hook up with somre COG folks....attend some tech sesions....bring good beer....you'll be golden.
I stress buy the manuals, they are the most important, and we cannot walk you thru every part until you become familiar of all the points of service outlined in the book....we can assist, but you need to become familiar with the stuff along side.