I want to invest in a 19 plex but my wife and is hesitant and I am somewhat concerned about the risk due to my age at 64 and the time it will take for the property to appreciate.

The type, age and condition of properties can influence the amount of reserves.  

Such as the desire to have impact windows, hip roofs, better drainage, the age of the roof ect.

Specially at such a young age!

However, the fireplace needs some lifting up from the aged look it has.

Download your landlord tenant laws for your state..Each person that's over age of 18 is listed on lease as tenant.. all equally responsible for rent.

For example I would want to know more about the building itself such as clear height, construction type, age of construction, is it sprinkled, how much office space?

Depending on the age of the house etc these numbers usually work for me In my area.

They're the ones that convince the landlord to sell their rental property to someone else, because the idea of cleaning up after their mess is just too much to bear for an absentee/ageing/uninterested landlord.

I want to know if by starting and using an LLC or Corp would I be able to bypass my age troubles.