1) If you wear a crash helmet, it's worth looking at the B6 which has a headrest set back slightly so that your head isn't pushed forward when wearing a helmet
2) Makes little difference if you use the same runners although you can tilt the seat with spacers.
3) IMO makes no difference with respect to comfort but it makes a big difference in the winter as Tilletts get very cold. The pads insulate you from that to a degree. We've got Oxted ones.
4) I resused the leather seat runners but you get some box section ali non-ajustable ones in the Tillett kit. Tillett do their own version as well.
Edited by - Shaun_E on 22 Aug 2012 14:37:36