I inherited some nice matching furniture from a tenant and decided to go big with full kitchen, linens, nice tv, WiFi, etc.  

For example, nice carpet or even hardwood may work well to match comps for resale, but durable vinyl plank is a good option for a rental. 

Cozy emailing me every time a rental deposit is made into my checking account. 

Can I mix and match income and expenses since technically I am working for myself in both situations, half my time at my tech gig and half my time doing real estate investing? 

You should be able to command a premium for new along with high deposits, first/last months rent, etc. as much as law will allow and market will bear.Just remember, it's exceedingly unlikely that the place will look new when you get it back...

Then we just match the type of investing that allows us to do that and achieve our goals.

If you do decide to get a down payment loan (a better term for this would simply be a personal unsecured loan) from your family - acquire the loan and deposit it in your account two months before you purchase the property, that will meet the seasoning requirements by the bank.

If you are using a realtor the earnest money deposit  is typically held in the buyers agent’s brokerage trust account.

Depending on where your property is located the buyer can ask for an extension of repair after the close of escrow and a deposit held for it. 

Free money is the best money If your employer matches 4%, 8% or 2% you need to match that number.