Luis, 1.5" should be plenty for a macro. If you feel the need to get closer than 1.5", maybe you should consider an underwater housing first because you'll either have to have it rght up against the glass or be underwater at less than 1.5"
Any lens you don't need is expensive IMO, because you could have bought something useful with it. I'm not saying you don't need a lens, I'm just strongly suggesting you get your camera, play with it, see if there's a weakness, then buy goodies for it if you see a void that can be filled with an additional lens. (feel free to consult with me first, lenses can get complicated)
I'm guessing with 8x optical zoom you may not need a telephoto lens either. The only sure way to find out is to get the camera and see for yourself.
Also, a telephoto lens may or may not work with your macro mode, it will probably have limited usefulness if it works at all. So you may not be able to get big close macros from stuff in the back of your tank, telephoto lens or not. For that type of thing, you'd need to buy a digital SLR ($1000 or more) plus a 180mm macro lens (another $800) plus all the other lenses (count on another $1000). My setup has cost well into the thousands, and I don't have the 180mm macro.
If you don't have Photoshop yet, I would highly recommend spending your money on that over a new lens- a lens may improve some of your pictures, but when used correctly, photoshop will improve
every single one of them.
Whatever you get, I can't wait to see some pics.
Travis