Here's how I would try this: Make a stamp animation of the howling wolf and place it over the movement tile where you want the wolf to appear. Now make a "trip line" of tiles which call an event about seven tiles away from your noisy wolf. The event reads like this -->
Stamp control = delete wolfstamp 01
NPC control = place Wolf 01 at X, Y.
Change map cell (for every tile in "trip line") to clear.
End event.
The stamp animation could have the wolf pacing back and forth and howling only once in the loop with a "play sound" flag.
You would have to make each wolf and wolfstamp unique or the trip line would change all the wolves at once (Not good), so you would have Wolf 01, 02, 03, 04, 05, etc.
As far as the healing goes, you may run into difficulties there. In other places where a healing potion is in the NPC's possession, the NPC does not "use" the potion but continually draws on it. The blue dragon in the Sapphire plugin to PoG is a case in point. If the dragon "feels threatened" he heals himself over and over faster than the player can do damage. This is a Coldstone bug. I think you would do better to make your wolf strong on defence and hard to kill.