Is it correct to assume that the ton-hrs represents the total cooling energy used for the specified months?
Yes, if the record is from a months periond.
Also is there a way to figure out what the max cooling load for the building is?
No
You could do 1000tonhrs with a 1000ton machine running one hour or with a 1ton machine running 1000hrs. But you could monitor 1 hr at peak load, then you know the max cooling load.