The Reserve ability is a player ability from the rulebook. It does not come from the Reserve Personality, so it doesn't fit the requirements for a Naval first-granted action.
The second question, assuming you use something else (such as Sneak Attack) to get the first action, will be that the Entrenched Poition is played after the Gold Cost of the Reserve action has already been paid.
The answer was perfectly clear and leaves no room for doubts, but I have a relatead question and need confirmation: Since the new Gold pooling rules of IvE, this string of actions is merely a minor hindrance, because as your next action you can Reserve the Personality again with the gold produce before; is that right?
EDIT: I don't want to get into strategy here, so ignore the risked part.