If the water bill is $100 a month, increase the price by 20% (or whatever you decide is fair) to compensate you for the time required to split and bill and to cover additional use when tenants squander the utility.

We attempted to get the sellers to take more money and offered them two additional options one with an extra $35k, via Subject To, and the other with an extra $70k with both Subject To and a partial seller carry-back. 

Sell it...especially since the gain is tax free assuming that you have lived there for 2 years.

What your ideal buy is changes over time as you gain experience.Post a property you've analyzed and do not plan to proceed with the address and your analysis and you'll get lots of feedback that will help you refine your own process.

Additionally, are there any other rules of thumb or key indicators you would recommend monitoring to ensure operational efficiency and profitability?

In a few years I was doing some big commercial RE syndication deals which is now what I focus on, in additional to some JV opportunities.

Overall this has netted over 3/4 of a million in equity in that time (sure, not a realized gain but still amazing) and produced true cash flowing properties.

Can you rent an additional garage space? 

That way the title company can determine if there are judgment liens or mechanics liens, in addition to title status, easements, etc.

Would it be best to establish additional savings accounts to hold deductions from my anticipated operating expenses (management, maintenance, misc)?