Yes, held is an action verb.
No, "firmly" is an adverb, not a verb. It is used to describe how an action is performed, such as "he held the rope firmly."
It is an action verb.
began is an action verb, not a linking verb.
action verb because you did this action (sent)
No. Held is the past tense (and participle) of "to hold." It can create a participial phrase, but it is not a preposition.
what follows a linking or action verb
It is an action verb.
Action verb
Action verb
action verb
An action verb
The verb stay is an action verb.