The circuits are clearly divided between the units within the breaker panel.  I

However, I’m wondering how cautious I’ll need to be with buying homes 100+ years old, or if I should avoid them entirely.The issues I’m most concerned about addressing are:-Knob and tube wiring-Foundation issues-Plumbing, cast iron pipes, galvanized piped-Lead based paint-Asbestos-Old single pane/drafty windows-Old HVAC systems-Roof-Historical preservation rulesI intend to leave the work of fixing most these issues to electricians, plumbers, roofers, etc.

Another thing I’ve noticed with some of the older homes is poor insulation, old single pane windows,  and lack of GFI outlets and other items that are not up to code just to name a few.

My question is should I spend money to upgrade the unit (double paned windows, new flooring, re-do bathroom) if there is not that much upside in rent?

Instead, I would eat all the losses.If you can show a friend or family member consistent prudence, a track record of success, and an incentive for lending, they will give you absurdly good deals, in my experience, and that said, I would be extremely cautious doing a buy-and-hold with a family member or friend because of the potential for strained relations.

But because of the strained family situation, if allowed in your state, you might want to offer to pack up the deceased person's stuff and place it in a storage unit. 

I've easily thrown ~$20K already, I've got a mortgage on the property, thankfully not causing to much strain on me, but regardless, i'm losing $ every month I'M Paying the mortgage and not a tenant.

Was asking 15k got em down to 7k. Row of houses with similar to identical exterior at end of the same block sold for 85k 3 years ago. Was quoted 35k for full rehab. 683$ property tax annually. I’m a very very new to t...

I have an atrium window in my house that has a double pane window.

I installed submeters just above each panel.  I