Of course you can print b&w multigrade. You can use the colour head, or filters with the b&w head. Ilford makes a set of 6"X6" filters that go in the filter drawer above the condensors. I have a 45MX that I use for b&w, and a 23C I use for colour. I use the ilford filters with the 4X5 for all of my b&wq printing.
You won't notice any difference between a componon S and a componon. They are both six element lenses, the newer S model has a slightly different f-stop dial, but otherwise has the pretty much the same performance as the older componons.