Back-end Access

We have a license for IFSM to connect to our QuickBooks but we have questions about the actual Customizability of the Interface.

I am familiar with the Custom Fields, Nomenclature changes, and limited additions to the interface... My question is, Can I use this platform to solve my "Service" department both On-site and On-field?

Another question is: Do we need to request Access to the back end? we need to customize and tailor this application or interface to our needs, and we want to use the backend for those specifics, since my company is too complex