Regarding the issues of finger direction in the second handshape... When performing an M, the back of the hand is seen from the TOP VIEW....see diagram below...

When you have a white space at the knuckle joint, you are looking overhead. The palm of the hand is parallel to the floor. From the Top View, with the hand projecting forward, the fingers pointing down actually disappear completely from view. So actually it would NOT be more natural to see the fingers below the square for the fist, when viewing the hand from overhead...The fingers disappear from view when directed down from the Top View....maybe a tiny tip of the fingers show, as they do in Adam's photo, but not enough to write them under the palm...

So how do we write this? We must write the fingers or the symbol cannot be read.

See diagram below. The first symbol on the left is used when the hand is projecting straight forward. Although the fingers are really hidden behind the hand, the three lines at the top of the symbol show they are bending forward from overhead....The middle symbol shows the hand projecting towards the front corner on a diagonal. The third symbol shows the hand projecting to the side wall, but you are seeing the hand from overhead.

All of them have the fingers projecting down. It is a symbol we memorize, and is quite well read and pretty standard around the world... smile... Val ;-)