I've got a Scout Group to teach this too so was looking for bearing block solution and found ASDA have little steel egg cups (four for £3). I split the top from the bottom and mounted the bottom (a more shallow cup) into a wooden block then put two of the now bottom-less upper (egg) receptacles inside each other (I found out the hard way just how hot they get singly) and whilst not very organic or Bushcrafty they do work.
With regards to wood I've found dry willow on willow to be a pretty good certainty. The issue I've really struggled with is technique, I was going hell for leather and whilst it appears counter intuitive I'd go gentle then alternate pressure with speed, so push down hard, relax and speed up, slow down and push hard repeat till you "dissolve into a pool of lactic acid". Finally don't stress about the coal again you'll think I'm mad but chill, get inside the oxygen tent and recover. Then gently place the smoulder coal in your tinder bundle (smould to quote Rob with a B on youtube) and again gently blow "ta dah" impressed a load of townie kids enough to put down their X-Playboxiiis!!! Any outbreaks of arson in the Midlands are entirely coincidental, your honour!
I'm afraid its either get coaching or spend hours and hours and hours in the garage. I did both - Thanks Jason at Woodland Ways!