When you say ‘market to my avatar,’ are you referring to a specific type of audience I should focus on? 

I'm an independent agent here in AR and I write a lot of rental property, with ~6 preferred markets and if the properties have some issues, age, claim history etc.

As it relates to lease end dates I've seen two things work here. 1) You can stagger end dates as mentioned above or 2) you can optimize for summer - this works better for us in areas where you see students or families with school age children moving to align with the summmer months.Separately, this is a great argument against month-to-month leases.  

Congratulations on building such an impressive portfolio at such a young age and achieving so many successes!

I'm a guy approaching middle-age, living in Chicago.

Many others on here have said the same thing, but at your age i'd focus on career.

My son (age 24) however, is an independant contractor / self employed and is trying to buy a house. 

Some carriers require limited water damage coverage depending on the age of the property and age of utilities.I would recommend at least 25% (ideally more) when possible and if you're limited to 10% you should make sure you cannot purchase another policy for a similar price.

Eg find contractors in ages out of state.

If you can get a better deal on the home due to age its a fine and if you need financing banks do not judge year built.