Beam systems and beam system tags

I have some confusion regarding beam systems, beam system tags and object styles. Any help would be appreciated!

Our office uses a kind of phantom line to represent joists in plan. I have used the beam system tool to create some evenly spaced joist framing. Even though I have my object style for joists set to a double dash line type, they appear as a solid line in plan. There are no VG settings overriding the object styles setting in my plan view. If I use VG to turn off the beam system on the model categories tab, the beam system tag disappears and, when I mouse-over, the beam system outline is unavailable for selection but the individual members making up the beam system remain visible and selectable.

Questions:
Why do the beam system tags disappear when I turn off (visibility) for the beam system (model category) but the beams (joists in this case) remain visible?
Why do the joists created as a beam system act together as a system and also as individual elements? (And why doesn't the system have object handles to modify the limits of the beam system in case a supporting member moves?)
How do I change the line style of the joists in plan? (They don't adhere to my object styles setting.)

Thank you!