I would think it's hard to optimize a business around doing $20K loans as well as $30MM loans. 

Well your already an investor.Download wholesale books, don't stop learning, meetup.com, attend webinars, view the education lane on the menu bar, etc.Happy Investing and Happy Learning!

2) the placement of the fridge does not seem to be the most optimal being right next to the back door.

I would rather have great cash on cash returns that I can reinvest and the ability to optimize the property cash flow rather than the sole purpose of having the properties appreciate.

I try to optimize around what saves me time.

With that in mind, how do we optimize our cash vs. car loan?  

Leveraging produces greater overall returns, less cash flow, and increases workload since you are controlling more properties.De-leveraging reduces returns, increases cash flow, and decreases workload since you are controlling fewer properties.Pick your optimal point on the spectrum for your own goals and values.  

5) I don't know what I don't know...what else should I be asking/knowing to optimize my performance in any given market? 

I'm trying to determine an optimal process for acquiring units and I wanted to get opinions / suggestions.

They should be able to refer you to a few agents who have experience working with investors and can help you understand the market & comps better.While long-term investing may not be optimal for most, a huge positive from it is that it takes away the emotion from investing, so you will rely more heaily on your numbers.