If I understand the question correctly, the confusion exists because the assignment of volunteers to an activity is managed. To come up with a clearer title for this you should try to make them more descriptive like Assign volunteers to activities.
Is the User using the System or is the System using the User?
A System using the User would ask questions of the User. Whereas a User using a System would follow clear, concise instructions to carry out their tasks.
It depends on the content of the form.
First: If the inputs are different which the user is going to submit then go for questions.
Second: Imperative moods is something which allows the user to relate well with the service has been provided by the process on a platform but as a user, I have done the mistake to give wrong feedback in terms of mood.
I would add to this that whilst you might think new / add / create are all equally viable. You won't know unless you test with users.
Recently I worked on a system where we used "create" in the context of a computer network. Our developers all thought "create" made sense, it made sense in their mental model. Their view was "the user has something they need ...
Create X: when you need to put effort into creating something - may involve some inputs without which you cannot create. Create X can appear outside the context of X as well.
New X: New, when the creation is instantaneous. New when you already in the context of X's parent.