Is there any way to add sword blocking and sound options. For example, to disable the critical attack sound?

The block hitting would be cool, and I can imagine how it might be done. By forcing clients to load a custom resource pack that adds a new model to swords that is triggered when you right click. Then your spinting would be reset etc.

Attack sound configuration options have been added as of release 2.0.1.
As for sword blocking: The general goal is that clients do not have to install any mods to play on servers that do use CombatEdit. I don't have experience with creating resource packs, but I would imagine that a different model would have to be triggered by changing the item stack, which would mean that for the blocking animation to appear, there would be a delay until the server has registered and responded to the right click action, which, depending on your ping, might not be great.
I have another mod thought - CookeyMod - which has an option that replaces the shield blocking animation with a sword blocking animation if you have a tool item in your main hand and the shield in your offhand.