Also are there any recommendations for brokers as she is starting out? 

Every system you try will have flaws, or you may salivate over a feature that appears in other software.Some familiar names are mentioned frequently: Stessa, Apartments.com, RentRedi, TenantCloud, Innago, RentManager, Avail, Rentec Direct, Doorloop, etc.I recommend conducting thorough research on each app online to understand their offerings, pricing, etc.

First, you should recognize that investing with friends or family can be risky, which is why most people recommend you avoid it.

Did you work with any real estate professionals (agents, lenders, etc.) that you'd recommend to others?

Maybe I am misunderstanding or wrong in some way, but I would definitely reach out to your accountant, or a good one in the area as they can get a full overview of your situation and recommend based off what is required in Missouri. 

What cities would you recommend as opportune areas for BRRRR?

Here's some steps I would sort of recommend if you start:1- Investor Profile: We always do it with our banker, but less often in real estate.

I would seek them out and then do your due diligence on them i.e. check references etc.

Does anyone recommend a good solo 401k company i can use?

Hi Benjamin, I typically recommend owning your own primary residence before investing.