OM, Cap Rate, Performa question

New in commercial real estate and need some advice.  I have been going through a ton of OM and I noticed that almost all of them sells you on performa and potentials.

What's a rule of thumb on cap rate and how much performa numbers do you look at if at all? On the NOI, do you calculate it based on gross minus the expenses or to subtract the mortgage rate on top?

Last, do you offer based on the cap rate and what is the general structure of the lease to increase rate increase without alarming your current business tenants too much?