Wow - quite a collection of Nortons you got there

Sure - it would not hurt at all to do the pencil grid - if the stone is flat the grid will be gone in just a few seconds and you won't have used up much of the hone.

Never used a prep stone either, so I can't help you. But you will do well by just soaking the stone and honing away (without it).

Tony Miller (the well shaved gent) makes fabulous strops - can't go wrong with him

Good luck
Ivo