If your realtor doesn't have a sophisticated system for querying the MLS a lower-tech method is to have the agent do a full CSV dump of the MLS for SFR and send it to you after stripping out the non-public data columns. 

Now I understand having a system for each property and will remove the emotional attachment to the property.

Make sure you get the sewer line scoped, electrical systems, and galvanized pipes and plumbing or all common issues with older homes.

When you say flat roof, hopefully you have a slight slope, because there are "flat" roof systems using modified bitumen (peel and stick nowadays) or tpo.

Starting smaller has several benefits; if you made a mistake, you did not go all in $ wise, not as much demand on your time, lets you figure out what 'systems' you need (for the property and yourself), etcBest of luck,Oren

I’m currently looking I to a property which has a septic but no septic records are found within the county’s health system.

I've heard of areas where there are multiple MLS systems within a single county.

building systems to become more efficient 

I’ve learned through me other ventures that it’s all about systems and processes.

Have systems in place for EVERYTHING!"