I think that the Viso system was designed for the compulsive personality. It is a "massive" system - you can spend a long time collecting the various pieces for it. Get one of the Leica books (Morgan & Morgan) and they have this chart with pieces that can be adapted to it!
As a starter kit, get the II or III (the III is easier to put on the camera) and a ring that will allow the use of 39mm LTM lenses (you will need the helicoil for that). I find for macro - the bellows II work the best as you can easily find the various adapters - including the 39mm or even the M-mount ring and that will allow you very close focus. Also scrounge around for an enlarging lens as they work very well as Macro (they tend to be corrected for flat plane image, but I have really not found it a problem anyway).
One of the best macro lenses (apart from the 65f3.5) is the lens head from the old Hektor 135f4.5. You need the tube for it though (usually $10-15) or, though more money, the Elmar 135f4 lenshead and the appropriate tube.