Also, once I've decided a possible sector to explore, what would the best way to learn more about that sector and grow?

Depends where you look with listsource though because the Waupaca market doesn't have enough data for me to filter for multifamily properties so I'm trying to find a way to get that data. 

This is an old link I found but serves well for our example) Let's assume that at any point, 10 percent of this inventory is for sale (no data found on this but any number should work).

You can buy that data from list brokers right here on BP 

The rates and terms are never as good as conventional, but you also have the ability to combine certain properties into one loan and save on closing costs.In summary, it’s great that you are thinking ahead and exploring options, but don’t get too bogged down or concerned with limits until you hit them.

That is always a must, and  then approach every owner the same with the same info and data. 

I think it is great you are exploring ideas and ways to broaden your experience and services to clients. 

The Agents have all the data to get you oriented on the current situation. 

A part of me is saying to vacate the premises so I can renovate and then get max rents in this market but another part of me is saying explore these prospects and still be able to increase rents a bit without carrying any reno cost. 

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.