Sorry for the stupid question, but I am getting my kit together now.

Right now I have the 7d, and so far have:
2 batteries
2 memory cards
-15-85 3.5-5f EF lens
- 70-200mm 2.8 with tele adapter
- 10-22 Canon 3.5 EF

- A manfrotto video tripod
- A manfrotto 'fig rig'
- and a still photo tripod
- case for the camera

My tripod set-up is a bit of a situation, the still photo tripod does pan or tilt smoothly, my manfrotto is huge and the 7d doesn't fit optimally to the base plate (which is the same) for the manfrotto tripod or fig rig.
I see a lot of set ups with rods, what exactly are they for?

I have a trip coming up to the maldives where I'd like to film some shots:
I was thinking about the following:
-50mm prime lens, either the 1.4 or the 1.8
- some screw on filters, neutral density and polarizing.
-water housing, possibly for renting but I don't know if anyone does that here in sweden
- Indie Slider deluxe.

Any thoughts?