Most of the answers to the basic questions you're asking have already been answered here numerous times.There are plenty of free guides here on Bigger Pockets - starting with "The Ultimate Guide to Real Estate Investing" https://www.biggerpockets.com/files/329/download.

You really need to balance the opportunity cost of the interest you'll save with the returns you can make by investing that $400/month or however much you can scrape together.If you want to get real nerdy, you can download a loan amortization spreadsheet, plug in the extra payments, compare the interest saved each month versus what it'd be if you keep the loan as is, and discount the NPV into today's dollars. 

Try the following link: https://www.biggerpockets.com/landlord-formsYou should be able to download them directly from there. 

US Legal Forms sells a contract/disclosure package for $60. https://www.uslegalforms.com/fl/FL-HOME.htm In California you can use the free FirstTuesday forms: http://journal.firsttuesday.us/forms-download-2/

I just recently downloaded the entire data set from the Dallas County Appraisal District. 

Before you transition to a new tenant, make sure you complete a move out checklist (you can download one as part of @Brandon Turner landlording book extras) and send it to the former tenant.Not receiving 30 day notice from a tenant is a common problem.

Thank you Paisley & Russell I am downloading the app now.

I found a robust 5 star form for income and expenses that you can download, I thought it was really good and just started using it.

there is a free downloadable pamphlet and waiver, it should be a part of all of the packet of documents to review and execute with all tenants.On the E Coast I think you would risk losing out on some great opportunities.Pamphlet and waiver-https://www.epa.gov/sites/production/files/2017-06/documents/pyf_color_landscape_format_2017_508.pdfhttps://www.epa.gov/sites/production/files/documents/lesr_eng.pdf

Before you do anything download your local landlord/tenant ordinance, or state statute to see what your rights are as a landlord.