The issues get a little deeper, but the key takeaway is that careful planning is very, very important.  

On paper, the plan here is that you get some rent from Section 8 directly and some from the tenant.Are you still getting any rent from section 8 ?   

I plan to live in the ADU and rent out the main house.

I was planning on focusing on small multifamily properties (duplexes, triplexes, and quadplexes), but I'd be interested in hearing people's' thoughts on the best investment type for the area.Thank you for your time.

Each investor who evaluates your deal will have their own plans for it in terms of rehab & contractor pricing.

However they know they are  just feeding people that have no clue what they are really buying -  They will take a automatic mailer you can to on your own and fancy it up and put a cool word next to it and Boom Sold!

As for the rodents, call a company and have them come out and deal with it...take photos before and after so if the tenant does something (ie puts out more rice), you can show that the tenant is deliberately doing things to attract rodents. ya we planning to call the health inspec saying the fridge is their to use but if they make it dirty and smelly we cant control that and its their responsibility.

But this doesn't happen automatically; Georgia law lays out a specific process that must be followed.  

As a businessperson, I'm not planning to hold any mortgage for 30 years.

A guy with some discipline, ambition and planning is going to make a great living going forward.