[Neus]

Traps behave a bit differently with EI. Blazing and Freezing won't do anything for the trap itself unless it matches the element, in which case it increases the damage by 50%. Galren increases the damage the trap deals by 2*Rank (it does this for a lot of skills). Raging increases the placement and activation range, as you noted.

As for Swift traps, I forget what they were supposed to do and apparently no functionality was ever programmed. I think I might make them 'attach' to the person who triggers them before they explode.