No, it's not normal behavior. Weres of the same type (or possibly even restricted to the exact same curse) are supposed not to fight each other (but it still happens). However, I think it's been seen before. It might be that turning into a were doesn't abort some (not identified) activities, or it might be something completely different.
A gremlin trap (a lever connected to retracting bridges causing the gremlin to fall into cage traps on the level below) usually requires a lot of traps on the level below, with one trap on each tile the gremlin can fall onto (I think my latest iteration had 14 traps).
Dodging can result in dorfs getting caught, but capture probably requires the dorf to get stunned.
If a dorf is trying to perform a task and then is burrowed at a location where the task cannot be performed the dorf either produces cancellation spam, silently get rooted in place while trying to perform the task, or, far to infrequently, drops the task. When a task is dropped due to burrowing the dorf then tends to stand rooted on the spot until there is a task within the burrow for it to take up (where eat/drink/sleep/socializing/... are "tasks" as well). Also, the buggers can start socializing and praying if they happen to be within such zones, even if outside of the burrow, or when the "I've finished a task and now wander off 10 steps in some direction" movement ends them in such zones. That wandering off can also have them escape burrows (and then get rooted outside).
Babies do not obey burrows, and mothers have no higher priority tasks than picking up their babies (I'm not sure about mood priority here).
I don't see sleep catching of the mother as useful, unless it somehow catches the mother only. If both the mother and the child are caught in the same trap you can only release them together (and yes, it's possible to catch more than one creature in a trap, as it's happened to me on a small number of occasions, but not in any controlled way. Presumably, all the creatures have to somehow enter the tile in the short interval before the trap is evaluated).