The real inflection point comes at around 75 at which point it makes financial sense to hire on-site property management.

If you want some retirement money then it might make sense to invest in a few SFHs.

I want to know I have someone to reach out to if a deal makes sense.

He may not want to lose his equity but that's exactly what will happen through foreclosure, so now is the time to talk some sense into him.  

I wouldn't modify a dwelling unless it made sense, not at the request of a renter.I would not add it to the lease.

Just because it makes sense to you doesn't mean it makes sense. 

However if you have a portfolio lender in your market who can size up the portfolio and do a blanket loan on the portfolio that may make sense. 

@Bryce Nerland Greetings,Not exactly what you were looking for but a few with similar topics:https://www.biggerpockets.com/renewsblog/2016/05/05/sense-pay-properties/https://www.biggerpockets.com/renewsblog/2015/04/08/buy-several-cheap-or-a-few-pricier-houses-investors-analysis/https://www.biggerpockets.com/renewsblog/2015/09/10/cash-purchases-real-estate/Hope this helps.

That said, depending on the investments you are making, your prticipation in those invsments, or the type of business you are running, it *could be* more beneficial to do so through an LLC.I say *could be* because you can tax the LLC as an S or C Corp. depending on how the tax bill shakes out, a Corp may make sense in certain situations.

If you keep evaluating properties in your market you will get a sense of what an average deal will look like and you will know when a better than average deal looks like, and those are the ones you want to move quickly on.