@Jeff Thompsonwhen you sell investment owned by the IRA - the gains are sheltered from taxes (because IRA is tax-deferred vehicle) and when IRA-owned investment produce income or cash-flow - it must flow into the IRA and also will be sheltered from taxes (unless the income is unrelated business taxable income). 

A 401(k) is generally the better vehicle, provided one qualifies for it.A strategy that could be used is the use of a 401k loan - i.e., a loan from the 401k - which can be used for any purpose.

I don't look at mutual funds as a vehicle to create wealth, but more of a place to KEEP existing wealth where you can get a modest return so your wealth doesn't get eroded by inflation over time.3.

Chris Mason  manufactures of Of these units by ALL means made multi family duplex units I have bought and installed many .. in Oakland no less.as long as they are affixed to a Permanent   foundation and removed from the motor vehicle registration they are considered stick built homes..

3) What vehicle would be my best option for this scenario?

It's a $35k car, but federal tax credits for electric vehicles make the monthly lease payment low.  

the benefit is that you can run multiple investments via your self managed investment vehicle.  

Also, If you pay off your mortgage early and truly own your house the ability to leverage decreases and you forfeit the ability to invest that money in other vehicles that would ideally bring in better returns than the money saved through paying down your home.

I am pretty sure I take all the deductions I'm due and I've vehicles such as as solo 401K, self-directed IRA, Roth, etc. but I think I might be missing out on larger-picture strategies for investing and tax savings.

I thought I would present this situation to the BP community and ask their advice and opinion on the whole concept of paying off debt versus using Real Estate as a vehicle to help you reach your goals.