Expected the unexpected, I was in your shoes a year ago, without any MTB racing experience, Here is what I encountered:
Three that went balls to wall from the get go
A couple that started mild then kicked up after a few laps
Some that mainained a high pace the whole time
Some that yo-yo'd the whole time fast, slow, etc.
Some dead flat, some with some rollers, some with a nasty hill
It seemed like every race was different, except for the fact that I had a blast whether I got dropped (most of my first ones) or hung in to the end (most of my last ones)
The first one I watched was the one that started right before my first one, it was women and the men were very different.
Still that largest group I have ridden with outside of racing is three, so take that for whats it worth. I have two young ones, a full time job and just train when I can. I choose do to my riding at 5:30 in the morning or whenever nap times hit, tough to schedule in group rides.
Just race.