Would soft or medium be the norm with cold water
As above. Wont be using 6 brushes. Don't want to spend over £100 on brushes and only use 1
This would really depend on your own preference as both would work well with cold water. In testing we have found that users often preferred a version slightly softer than they usually would use due to the shape of the bristles.
These brushes need very little pressure to scrub well and are very fast on the glass.