Check zoning and access.5. 

I think we’re looking for a single family property, but with the option of renting the basement out based on the zoning laws of that specific location 

No zoning in the counties.

You could defer the gain from the sale of the business operation under a Qualified Opportunity Zone Investment Fund. 

If you have to think twice about the monthly holding cost, that is a red flag.Unless you're getting the home at a discount, I would look elsewhere for your first investment, preferably something that you are at-least breaking even on.

I'm wondering would it be smarter to wait and buy a quadplex with an FHA loan or 2 duplexes with one FHA and the other conventional.Also, if I could find a duplex that is zoned for 3 or 4 units (which I believe is R3 and R4?)

Can an unrestricted AG zoned be used for RV /tiny home park in Houston, Austin and Dallas?

How big of a red flag is this?

Shouldn't raise any red flags under a certain dollar amount coming in (usually it's one large transaction, or in the amount over $5K that gets held for verification by the bank's holding fees - again National Anti Money Laundering laws)  but if you needed to leave it set for a few days until it did clear, still shouldn't be an issue unless you're using these funds for immediate use. 

The work may have been completed without permits which can be a major red flag and could cause problems in the future.