I guess I assumed that any lever would work. which goes with which? also, does one have more power that the other? does one perform better in the snow?
Yes, different "pulls", as A.S. said. But it isn`t really very complicated- with only a few exceptions, levers made for drop bars (slightly larger diameter than flat bars) will work with "roadie" sidepulls and with old style straddle wire cantis. Those levers include the brifters that come on most new road bikes (STI, Campy Ergo, and SRAM Doubletap). Old mtb levers, from pre V-brake days have the same pull as road levers. Most new mtb levers work for mechanical discs and for V-brakes (same pull for each of those) and many mtb levers can be quickly and easilly switched from one "pull" to the other. None of my Avids or Tektros are switchable, although the adjustable pull on SD7s comes close enough that I`m using it for the wrong brakes on one bike and haven`t had any incedents yet. I`m pretty sure that all Shimano mtb levers can be switched- somebody please correct me if I`m wrong. If in doubt, check the product specs- Long Pull is for Vs or mechanical discs, Short Pull is for straddle cantis or sidepulls.
As to strength, many canti gurus claim that propperly set up straddle cantis have more power than Vs and others claim that Vs have more power, period. In the real world, the difference is small that it isn`t worth worrying about- with modern alloy rims and good pads, they both offer excelent modulation and way more power than any brakes the clunker riders on Mt Tam ever dreamed of. In my experience, vs are in fact easier to set up and adjust than straddle cantis, but at the rate I change pads, I don`t really care. I currently use both types and don`t notice any difference in any aspect of how well they work, including in the snow. If you think you really need all the brake you can get, I suppose discs would be your best bet, although I`ve never used them and probably never will. Not that I have any doubts about them, I just plain don`t need them, don`t like how they look, and don`t want to learn a new skill set when it comes to installing and maintaining them.