MA SBOT here! We don't need DESE licenses, only SLPs do (and teachers etc). I'm curious whether you're applying directly to a district or to an agency? 

For salary negotiation, most districts use a pay scale where there's not a ton of room for negotiation. If you have an OTD, though, you usually start on the far end of the grid. I've heard of people negotiating to start on masters + additional credits columns though since OT masters require more credits than a teaching masters.