Personally I went with the Heine Sigma 180. Love it. Totally lightweight and very easy to use. Also keeps a charge for a long time. The Keeler was really nice too, but waaaaaay more expensive and a great deal heavier. The Welch Allyn BIOs were all right, but felt kind of cheap - also, a friend of mine bought one and has had to get service on it 2 or 3 times.
As far as the lenses go, for the BIO you use lower powered lenses, i.e. 20D, 30D, etc. Basically, the higher the lens power, the lower the magnification, but the bigger the depth of field. Our professors recommended that if you had really, really, really tiny hands, get a 30D, otherwise a 20D is fine. The 90D, 78D, and superfield lenses are for slit lamp biomicroscopy. I love my Superfield - and I also tried one of my friend's lenses called a Superpupil that was really good too.
As far as for not needing this stuff, maybe not, but how will you really know unless you try it out. It can't hurt to get it while you're in school too, since I know at least at my school, we get at least a 40% discount on what practising docs pay, which is a huge deal for stuff that doesn't really ever go on sale.
Hope this helped you a bit!!