realsorryman You have a really nice example of an American bike. Don't replace what isn't broke. Use it as your learning mule. If you are careful and not force anything, it is unlikely you will damage anything that may be damaged already. In other words, hide your hammer for now.
What tools do you have? Are you mechanically inclined?
polymorphself s list is good. follow it.
Pick a area where you are having questions and post on hear with them. We will walk you through it. Unless someone can give you a good reference for an LBS, I would avoid them. But that depends on your mechanical aptitude.
The "freewheel" is the set of sprockets in the back the chain rides on. Some call them "cogs," not really, they are sprockets. They are sometimes referred to as the block. In any case, at some point you should clean that as well. Searchin on BF will give you a wealth of info on this topic alone. It may not be a typical freewheel as ITrek did sell these bikes with
Helicomatic hubs and freewheel. To remove one requires finess or the correct tool. The LBS that has a tool will be one to trust.
To begin with, show us a picture of the RD problem you think you have. Lets start there.