I'm currently building a frame for my a level project completely from scratch....done loads of research and cad work, but cant really be bothered to type it all ou there email me / msn me at alexdark2@hotmail.co.uk if you want a chat.
I think less pressure - more bounce to a point anyway... High is 20 i reckon, i run about 17 rear, 20 front. In future, use the Search function...that's what it's there for
Yeh that looks fine, bear in mind that that cog is made from aluminium and so will wear away far faster than a Cromo steel version. Thread size etc it looks fine No lockring needed, maybe a spacer for the cranks if you run no bashring though