Yes . Get checked on board have something to eat, go ashore ,GET A TAXI, ASK PRICE FIRST! ENJOY .
Leave the dock at Palma & go into Porto Pi. Catch the Number 3 bus straight into Palma Town Centre - only €1.80 single.
I like the sound of the Bus
Hi, other options to the bus and taxi, are walking (it took me and my partner at a very gentle pace 1 hour). There is also the hop-on/hop-off tourist bus which stops just near where you dock and that costs 13 Euros. Sorry, haven't been to Messina so can't comment on that. Enjoy.
It all depends on how quick you embark the ship, but if you have time walk from the port buildings over the main coastal road and up to the road that runs parallel and behind the hotels, buses are €1.80c and you will love Palma, but don't forget to be back at the ship 1hr before sailing time.
Yes Palma is very accessible from the ship.
We visited Messina last year with Island Escape and walked into town from the ship in 10/15 mins. Make sure you are in the main square at midday, the actions and chime of the clock tower are not to be missed !