Bonus depreciation, transferring regular expenses to business expenses and relying on repairs more than capital improvements are good strategies. 

Repairs and other service work should be done during regular business hours.

I have them do elevation changes, site plans, and landscape plans regularly.

A Solo 401K avoid this tax.In non-Roth retirement accounts, you will move what would have been Cap Gain to regular income in the future when you distribute (RMDs!). 

Separating electrical will be a different process and cost than separating heating where you might need to run separate natural gas lines and purchase individual furnaces.

How does it differ from wholesaling regular properties?

I have met people who manage the work themselves but that might be really hard if you have a "regular" job that might interfere with such things. 

So, our regular plumber mentioned that the price of water heaters looks like it's going up significantly. 

I've been debating to turning it into condos, but don't have much insight into establishing an HOA or anything of that nature

What i'm struggling with is whether it's worth trying to do a non-recourse portfolio rental loan that combines all these into one loan. advantages are mainly that i get to wipe off the recourse nature off the record, can structure a 10-year IO period and ARM after that; however, the cost to complete is meaningful - 1% origination fee, $2-4k closing fees, new title policies cost of $15k or so, higher coupons of 4.3% +/-, prepay penalties and non-assumable, probably more difficult to selloff properties individually.