You are 25, you aren't "falling behind," most 25 year olds still live with their parents. 

We’re a home ar Chuitecture firm in LA County in Hawthorne and considering splitting our primary residence lot and building a larger stand alone home for office/ home use / Elderly parent use in the short term and potential rental conversión or sale long term.

KISS is a mindset we often refer to when we think about improvements.

There's nothing wrong with "going big," so please don't let me discourage you, but- I find that mindset keeps people from taking reasonable, simple steps towards financial freedom because they can't grow as quickly as they think they should. 

Love that you and your wife are focused on building a solid foundation — that mindset will serve you well.Books/resources: The Book on Rental Property Investing by Brandon Turner (a BP staple), and The Millionaire Real Estate Investor by Gary Keller are both great next steps.Buying rentals vs personal property: biggest differences are how lenders underwrite (they’ll look at rental income potential, reserves, and DSCR ratios), and how you should underwrite — run the numbers first (rent minus expenses) instead of buying on emotion.Getting started: a HELOC can work, but make sure you’ve got good cash flow margin so you’re not over-leveraged.

This implies that in CA you do not desire to have been renting the property if you plan to continue to live in the property; you will be better served if it was the primary residence of the deceased parents.  

that kind of mindset is exactly what gets people far in this space.

Stick to local or a strong secondary market.Cash buyers = build this list like your business depends on it… because it does.Novations = advanced tool, not where you begin.At the end of the day, wholesaling requires marketing, patience, relationships, speed, accuracy, and a strong mindset.

There on an upward trajectory. 2nd is Tenant Mindset. 

Answering your question, I'm not sure what your entity structure is but our bookkeeping firm (specializes in REI) usually recommends a checking account (minimum) per subsidiary entity and for your parent entity.Ideally, you'd have a credit card per entity as well, but this isn't realistic once you scale past a certain number of entities, just like having 1 bank account per property past 10 properties isn’t scalable.