Wow! Michael that is an awesome WHY and a very noble goal. I am just a tiny bit further down the road from you, I'm 29 w/ two kids (6 and 3). My wife has been a stay-at-home-mom for the past 4 years and believe me, this is the way it is supposed to be. This sort of family dynamic allows you, the hunter, to stick w/ your strengths as a provider and allows your wife to stick w her strengths, nurturing and raising children (don't get me wrong, parenting is a team sport).
As far as real estate, $4,000 passive income is a lofty goal, your first step is doing the math of exactly how many rental properties you need and what type (SFH or multifamily), as well as the market you can invest in. Hopefully the Clemson area is conducive to income property investing. So if your goal is $4,000 a month and you can acquire properties that cash flow $200 each after expenses, etc. than you will need 20 properties (or 20 doors, if it's multifamily).
To simply buy that many properties would take a lot of capital, so you may want to research more creative strategies such as owner financing, subject to, owner financing, etc.. These would allow you to acquire (or control) properties much faster than a conventional purchase requiring 20% down.
Also, since the cornerstone of real estate is actually finding good deals, you may start your REI career via wholesaling, which can generate a substantial side income (although active, not passive) that you can redirect back into growing a portfolio.
Always good to connect w/ other Gen-Y REInvestors, keep in touch and wish you best of luck! Keep me posted on your journey!