Being able to pick their brains is always helpful, both their successes, red flags, war stories, etc.And as Jonathan mentioned, the very first step of actually taking action is knowing how much money you have to allocate to buying a property, fixing up a property (if needed) and how much a bank will lend to you.  

This is my first purchase (don't want to do anything stupid) and the rents could swing 600/month depending on what I'm allowed to do in the basement - I'd be in the red from a cashflow perspective if I can't duplex them.Am I rolling the dice here / do you not typically find out for sure until you close and begin renovations?  

More secure and stable than an STR (also less competition) but you aren't in the red like you'd be with an LTR. 

Any additional due diligence questions or red flags I should look out for. since its my first time to invest in multifamily3.

They city will red tag it and require you to upgrade everything and get a Certificate of Occupancy before you can rent it.

Heck go to the casino and put it on roulette wheel of black or red. 

Both the daughter and Dad have excellent credit history but feel this is a red flag. 

MInut has a low average review (mid-3s I think) on Amazon which is a bit of a red flag. 1 per room at a total of $60/month sounds excessive for something that is not likely to be a common occurrence. 

Major red flag for me that they won't give you one.

Hopefully, some others see this.Yeah, I would say that's a red flag about the LLCs because usually when an LLC buys and flips, they sell to an end buyer/homeowner, not another LLC.