Welcome to the world of real estate investing, and congratulations on taking the first steps toward learning about this exciting space!

I have them on my properties.

I am looking into buying a duplex in Hyatt Park and wanted to get some advice on what contractors/suppliers I could contact that have investor friendly pricing for kitchen cabinets, countertops, and bathroom vanities.

There are more options for renters so it's putting pressure on rents btwn 10%- 20%.

To thrive in real estate investing, you must maintain a firm grip on your finances.

There will always be people who want to rent by one but I wouldn't count on one raising property values - I would in-fact assume the opposite.

It almost feels like they make it difficult on purpose so they get extra revenue on late fees.

Would need to know a bit more before giving a specific direction but it is usually best to hang on to your property and not sell whether you expand on it or rent it out and purchase a bigger property.  

Or how to put the unpaid rent on their credit score

Skip the class and go straight to learning on the job.