Benefits can be expensive, and they only pay you for the 40 hours because it’s a salaried rather than hourly position. They just want free labor at the expense of the employees’ sanity.

Wiktionary suggests both “fixing to” and “fitting to” are used synonymously. Fwiw, in Tennessee, I only ever hear “fixing to”. As someone who learned English outside of the southern US, it makes little sense to me also. But what makes even less sense to me is people saying “trying to” to mean “want to”.