Unfortunately, I don't feel safe getting on a ladder and going on-top of the roof.Should I hire an inspector to have him give me his feedback?

I have not lived in AZ for many years, but when I did live there the building inspectors were on top of things. 

You could also hire an inspector to do swab tests around the house.

So this saturday I will be walking 4 different properties with the current owner, my realtor, inspector, and my contractor.

Perhaps a nice 1950's built bungalow.Always hire a 3rd party property inspector to give you an unbiased feel for the home.

Workers charge more and la inspectors are not your friends.

For example, it totally makes sense to me to do lead certification for the first time, but if I ask lead inspector do lead certification for the same unit every 3 - 4 months, or few days for airbnb type rental seems not feasible.

City inspectors are tough and the weather has been tougher.

Check in with your local building inspector and get a clear reading on it.If you build without a permit when one is required, the building inspector can make you tear out the unpermitted work. 

They may not be hiding anything but a good inspector might find that they are not even aware of.