Attacked

I changed the spine of my armature to just a spine and chest (like the imported armature) but had to redo the weight painting of the chest because when I deleted the spine bones the weighted body was also lost.

I continued applying constraints but found problems with the hands; they would snap against the wrists and just look deformed, as well as rotating by its own accord. I altered the position and scale of the arm bones, and even deleted the other 2 parts to the hand but found the best solution was to deselect the use tail option and the followed the lower arm movement, which looked fine.

I again had problems with the position of the armature's hip and shoulder bones, and for some time I changed the position of the spine and chest moving the neck and head positions.

I believe in this video the overall balance looks better but there are still so many things to adjust, with the hand going through the head, and slight position problems.

Importantly though, I discovered a way to see more of the sequence through the camera, I changed the camera lens setting from 35 to 20. There were still parts that disappeared but it meant I didn't have to keep keyframing the camera movement and sacrifice seeing parts of movement.

I can use this to show more of the walking and other things I needed to zoom out for.