Newbies with $700K Cash

[Sarah Schmidt]

Newbie here! My friend and I are looking to get into real estate investing. We are in Austin, TX. She has $700k cash and is unemployed. I have experience running a business (successful passive income biz on Etsy), am a CPA, and have a FT job (sales so its flexible not 9-5). Both 700+ credit and desire to build a successful long term real estate business together. 

$700K buys a duplex in Austin or possibly a SFH with ADU to BnB. We were thinking we'd house hack one unit and rent the other. Are we starting too small?
Also how would you split equity/cash flow? She has cash and time during day, but I would do bookkeeping + set up/run BnB site + have reno skills. I am approved for $450K mortgage (SFH not sure if that will increase for multi) and can bring that to the table as well. 

If our goal is to acquire a portfolio of properties how do we best start and use the cash available? Go big or go home right! TY