@Lev PaleiWith the right systems, a good handyman could self-manage and do the upkeep on maybe 20 properly hardened SFR before maintaining them seriously started cutting into his time.

It has been split 3 ways, not sure why, which means that 2 of the units have the heat controlled by another unit (if that makes sense).

@Raul Velazquez Jr Everyone is different - some with an accounting background or general knowledge about accounting can handle tax prep on their own with one, maybe two properties.Others like to put systems in place and hire out right away, to free up there time to spend on more valuable tasks and actions.If the latter describes you, I would say start speaking with real estate savvy CPAs ASAP.

I suggest a condo because the maintenance is minimal, the sq ft is limited, so you’ll be able to control your expenses (typically) better.

Btw if its any help im from Texas.Whomever is on title has complete control unless there is a contract that says otherwise.

You might be better off that you learn more about  partnership memberships where you stay in control and just offer them income without being into working on the property's day to day operations. 

We have the intentions of keeping this duplex long-term as it is the start of our real estate investments, but want to know whether it is a wise investment to upgrade to central heating and air in Ohio given that we will have to run two sepearte systems and all duct work in addition to upgrading the electric box.

He could make a (reasonable) case that things out of his control lead to delays.

You are controlling your 401k, you invest your 401k, and you will benefit from your 401k in the future (not today).

After you have the septic systems inspected and everything checks out you can assume each one pumped every 5 years (assuming 1:1 septic to home ratio).