It may be worth a call to a rep who can give you a tutorial and demo.  

Hi everyone,I'm getting ready to start a direct mail campaign to apartment owners.My goal is to purchase at least 10 doors in the next 12 months, and wholesale any other deals that don't quite fit what I am looking for.I'm planning on targeting some smaller markets in states that I think may receive less attention.Does BP have a tutorial on the best way to start this?

There are YouTube tutorials on how to find different kinds of leads, look there.

Although they were credible they would take you through success stories and tutorials of previous students who had scored big from using their services.

Is there a tutorial/explanatory video available somewhere and a standard letter I can send to explain how LOs work?

Is there a tutorial/explanatory video available somewhere and a standard letter I can send to explain how LOs work?

Should be plenty of videos & tutorials on youtube to show you how to use these functions. 

You'll probably have to compensate them for their time (something like $100) as you do not own the property nor have it under contract and GC's do not like having their time wasted with individuals who are simply seeking free bids and won't use them or are looking for a free tutorial.

I have seen tutorials on how you create a new invoice, and uncheck the original one, but I have no idea how to correct the matched deposits. 

There's not a lot of QB tutorials that are specific to real estate industry but a good RE bookkeeper/accountant should be able to guide you to the right direction.