Hi Kaz
You can purchse WAC's called sellosheen (that might be spelt with a C) either folded or flat, the others as airsick says, are renewed frequantly. Just do most of your scribling on the covered ones. Permanent marker sounds like a good idea, whilst in flight you could then use the chinagraph pencil so you can still write and rub!
Yes can see your aircraft!
110kts is just a tad slower than 120kts, which is equal to 2 miles per minute, if you have a 90kts machine you would be going at 1.5 miles per minute.
or @ 120kts it will take 10mins for 20miles, or 14mins/20miles for a 90kt cruise. If you interpolate you can figure out 110kts roughly. Lets say 11mins. So if you are thinking in 20mile sections you can calculate stuff in your head and leave the wizz wheel tucked away, or give it to your instructor to check up for you.
This is just a rule of thumb!
Hope I have not confused the situation!
Cheers Guy