The board should be mounted flush to the wall and not leaning at all. The 20 should be at the top.
It is also advisable to have a raised oche. If your oche is flush with the floor it is all too easy to place your foot or toes over the line without noticing.
Distance to the toe line
When measuring the distance to the toe line it is important to make sure you measure from the bull and not the wall. If you choose to measure from the wall you must ensure you have compensated for the thickness of the board. I find it easier to use the diagonal measurement 2.93m.
Ladies throwing Distance
Is the same as for men in ranking tournaments. In some leagues around the world, ladies throw from 7 ' 6" or 7' 0".