I am looking into converting the garage into an ADU and rent it out for additional income.

You can take participant loans from the 401k, you don't need the additional expense and administration of an LLC to have checkbook control, and there is a built in-Roth component if you'd like to make tax-free investments.

To keep things simple, we stay consistent with our percentage ownership in everything and that is reflected in our K-1s.For additional work I've done for our LLC, we will pay me "management" or "services income" and I get 1099's at the end of the year.

The apartment building is now a sweet additional income stream for us.  

But as far as additional income - No.

When they can see you manage positive cash flow on these investment properties, they would be happy to step in and help you purchase additional properties.

If your deals are over $1,000,000 there are some additional options though as they can almost qualify for agency debt.

In my opinion much more restrictive flood zone code devalues these properties as it will seriously preclude investors from continuing to improve properties and make additions such as garage apartments due to additional cost in building and lot prep. 

Additionally, it's well known by all the owners in this condo building that the wall units are a bit loud.I scheduled an appointment to have an HVAC technician look at it and he couldn't find a solution.

My services will in short relieve the heir(s) from additional emotional trauma stress and assist counsel or executor by closing the estate case sooner, save everyone some time so that they can move on in their grieving process as any loving family member would want.