Here are 2 key factors to prepare yourself for your entrance into commercial realm:1.

However with that said, can you take square footage from somewhere else to create a hallway or create another entrance into the bedroom? 

Renters like the private entrance, patio, attached garage, etc.

While I would like to buy-and-hold a SFH or multi-unit as my first entrance into RE, the competition in this market for them has been tough (I've met so many overseas investors at open houses!).

Id like to build a second story with a private entrance.

But I know this would probably have a higher entrance cost to get this going.As for cost comparison I would talk to builder to see what the difference would be and look at your return over the duration you intend to keep the property.

We immediately replaced the entire roof with money we received cash-back at closing, rehabbed all of the common areas (lobby, hallways, cafeteria, entrance), rehabbed the 3 vacant units, addressed the landscaping, resurfaced and lined the parking lot, implemented third party management (Vic Green Realty), and added a $25/m utility bill-back.

Private gated driveway with 3 power gate entrances, privacy wall from street and this home will have all the trimmings once completed.

I'm still not quite sure what all your after here, but if you're considering house hacking where you live in one side and make the other an Airbnb...preferably with two entrances.

We stepped it up a notch for this bigger home and put in marble kitchen floors (discount from a family member) distressed hardwood, removed most of the drywall, opened up the kitchen to the dinning, turned a 3/4 bath to a full and changed a hallway bedroom into a separate entrance bedroom.