To remove or install the drain plug, all you have to do is go under the car and turn the engine forward by hand until you see the plug on the torque converters. Your family tech member should be able to tell you more. In my case, tightening the drain plug fixed my problem.
Once the tranny is off the car for inspection, the shop should be able to tell if you need a rebuild tranny or just a seal job. You have to find a honest mechanic and to trust his findings.