Remember that doctors and commercial tenants will look for different property features vs. a residential tenant.

Ironically, the line of credit is currently at 3% with a lock-in feature for whatever amount I choose to use.

Find Bigger Pockets Podcast featuring real estate agents and listen to those.

It's pretty user friendly and it's free as long as you stick with the basic features. 

I like the search features: https://www.biggerpockets.com/search

You want to study what other investors and the builders are doing so you know what colors, features, styes etc are popular in your area. next is to learn how to get deals direct from the sellers and the MLS as well.

Does the commercial have any redeeming features or are they shells?

Do not out build the neighborhood or you WILL lose 99% of the time, ensure your finishes and features are in line with the area. 

I like the search features: https://www.biggerpockets.com/search

You need to look at recent sales of houses in the area that have the most common features - not just for the house, but for where they are.