A. Selected control nodes should be more visibly indicated. Their selected status is hard to see.
Agree. I'll see to it soon.
B. There should be a keyboard shortcut to toggle a mode highlighting richer bezier info on the selected path. The user would see, node number 0..N, degree, etc. for each node, near the node. This would be used in enhancement D, among other places.
There's a RFE to add coordinate/angle editing fields (for the selected nodes) to the node controls bar.
C. For multiple nodes sharing the same location, you should be able to keep clicking the spot to cycle through the various nodes, even if they're on different paths. This is probably a general 'drill-down selection' feature request, not just paths.
Alt+click for shapes "selects under". For nodes, it would indeed make sense to do something similar. However it's difficult technically. Please file a RFE, some day I may invent a way to do this.
D. There should be some control over how far along the path between selected nodes the inserted node appears. A toolbar slider going from 0 to 1 would be ideal.
No, simpler than that: just add a node where you click :) There's also an RFE on that. We just need to implement that.
E. The degree of each node needs to be more integrated in the visual feedback. I *think* that the change from square to diamond indicates degree now.
I'm not sure what you mean by degree. The shape of the node indicates its type (corner or smooth).
I'm not sure how to increase/decrease the degree of a particular node. The help tip should probably indicate how to do that when paused over a path node.
Ctrl+click changes the node type, or you can press "c" or "s" for all selected nodes.