I would recommend going with the lenses you want first. I use the 10-17 as my wide angle and am very happy with it. I kind of wrestled with the choice of the fisheye or a rectilinear and went with the fish. I kind of like the effect but my friends tell me I'm slightly warped anyhow.
I'm outside and around water a lot and none of my lenses are weather sealed. A little common sense precaution and you will be ok. When your camera is hanging from the strap around your neck or shoulder the lens is pointed down and unless it is pouring hard enough for water to flow over the camera it won't get in. You wouldn't be shooting in those conditions anyhow. Buy the weather sealed if you like but you can use most lenses in all conditions with a little care.
Another reason to go with lenses now is the current trend in the business to sell the camera bodies cheap and make the profit on the lenses. Prices have gone up on glass quite a bit in the past few months and they will probably continue to rise. The lens vs. body discussion goes on constantly but one thing is certain, a so-so lens won't produce better shots on a new body.