In my career in the car industry, I have made many contacts including tradesmen as well as business owners, including an apartment complex owner who is beginning to exit them due to obligations in his other companies.

The discussion here is that many of us are dealing with hundreds/thousands of transactions, and therefore Excel isn't sufficient for keeping track of finances.In your example above, regardless of whether it's one journal entries with 1000 lines or 1000 entries, the complexity is still the same if you're trying to use Excel instead of QB. 

NOI was estimated by calling the prop. manager and just asking how many units were in the complex, what the mix of units was, and how much each would rent to a new tenant for.  

The focus here seems to be either single family or large 50+ unit apartment complexes.  

Are QuadPlex properties appraised with comp sales like a single family or a duplex would be, or is it appraised using cap rates like apartment complexes are?

You might want to start off with small apartment complexes that are well built and do not need a bunch of work.  

I think that small apartment complexes can be a good way to start.  

I'm just trying to figure out what steps I should take to get to my end goal of one day owning a large apartment complex.

For instance, the area at 38th & Post has a bad reputation because of a couple of apartment complexes.

You might want to get small apartment complexes at first then get larger ones.