If I'm not sure if I'll be paying by check or will have to do payments, what do I fill out in the filing section? Do I go ahead and put I'm going to pay by check?

If you're wanting to file your taxes & there is a fee, you can choose the option of paying for it right of your tax return. This way there is no out of pocket expense & you have everything on file for the IRS to process when the time comes.