Thanks.Theyre mostly called infected.
You're correct- all except for bloaters and shamblers are capabke of running.
The brain is still located where a brain is located. The fungus acts as a sort of "shield" to it.
All infected can be damaged in the same way you would damage a person, because they are fundamentally still people. So you could choke out a runner, or stab a clicker to death. A blow to the head is going to be more effective, but may also take multiple shots if the fungus has grown enough to act as a form of armor.