Even with a great opportunity, trust is the foundation of any partnership.In my partnership, we had already worked together on multiple deals—me as the agent and him as the investor buyer—so we had established a strong foundation of trust.

Ummmmmmm...I've lived in California since 1990 and own multiple investment properties there.

Multiple outbuildings and cottages spread out among the property.

Let’s unpack your ROI question in a way that reflects the reality of your financing setup.When calculating ROI with multiple loans, you’ll want to include all financing components in your cash flow analysis.

Similar for bathrooms if virtually all are multi bathroom but you find a single bathroom, making it multi bathroom via new construction could be a value add.There are more sophisticated value adds such as add multiple adus via bonus density program.  

I've even paid for a subscription to have limitless access to all articles on multiple of these websites.

I've seen banks be very competitive with blanket loans that cover multiple properties and/or multi-family properties, e.g. 5+ units.Mortgage Brokers (obviously I'm biased) - Brokers have the ability to work with all of the above and can get you to the best lender for your scenario right away instead of having you waste your time with the wrong type of lender.

You can have multiple conventional mortgages and have a great credit score as long as you don't pay late or get too close to the maximum debt to income ratio.

I wish people would do some research on the forums before posting but I think people would rather make a post then search the forums to see their question has already been answered multiple times that day. 

Your best bet is to get on the phone, get multiple opinions, multiple quotes, and make decisions on the type of build before pulling the trigger.