Well, this is the first time anybody has ever even mentioned this...that would be a good reason there is no documentation explaining this...and there is not really a whole lot to say on this topic.The primary reason that you do not want to take your existing projects and try and implement the SF core logic is because SF changes the core of how a standard .NET app communicates with the data/application logic/etc., so there are some foundational components that would be really difficult to just "slap" in there.
Your best approach is to go the other way. Create a SF application from scratch, that is clean, then add your existing program logic into the new SF project a piece at a time. If you try and go the other way you will never totally work through all of the issues.
This is the approach that even I would take if I were in the same circumstances. I am sure that all of this will make more sense after training, but you will be far better off and happier in the long run to create a new project and then start bringing over existing programs and dialogs one by one. There is no "quick and dirty" way to do this.