My brief history:
Now some questions
While credit score alone can disqualify you for a mortgage loan I think it's important you realize that it has little importance in approving you for a mortgage loan and the real "heavy lifting" of the "work to be done" is in the long run of paying for this mortgage debt.
So please accept my constructive criticism and focus more on what it takes to obtain a loan, learn about the type of loan you want to have and begin preparing for that while you gauge your local real estate market place for properties and homes that will meet your needs. Generally speaking, in order to maximize your credit score you want to have 2-3 accounts reporting your timely payments to all 3 bureaus each and every single month----something it appears you may already be doing, but I think I'm answering one of your questions by stating that revolving accounts are ideal since they'll always stay open as long as you keep the creditors satisfied.
Now, let's look at other critical factors regarding mortgage loan approval so you are prepared to find the right loan that meets your needs.....
--stability of employment---(most recent 2 years)
--down payment amount and source
--estimated purchase price