Luggage is actually priority, but back in the E-jet days it was hard. From memory catering for return flight, then rush bags (i.e. ones that missed flight day(s) before), then critical medical supplies, then luggage. I can't remember if perishable freight (i.e. food) was before or after luggage. After that comes freight, priority for perishable. It is really confusing because people check in lots of fresh produce due to cost considerations, and you've got to try get that on before general luggage. A really difficult flight, I hated it.
It was not uncommon for there to be a big backlog of freight. Such was the nature of the route. I imagine the A320 doing regular runs has helped that since the E90s went bye bye. This is the classic example of "better to keep quiet" when it comes to bags not making flight. You can imagine how often you'd have a family of four or whatever, and three bags would make it but one not. You then have a fully loaded E90 or B737 belly to sift through and find three bags to offload, while everyone else waits. Then re-do the paperwork and fill up the tanks again, because that whole time you've been burning fuel in the APU that you just can't afford to lose on such a flight.
Sorry, veered off topic!