All of the above are correct. Chak is your best best.
The pier is unknown due to other ships schedules and availability and other variables.
The Capers the night before will tell you which pier you will dock at.
There is a chance the shopping expert person would know in advance so maybe ask him/her when you get onboard.
I use a company (a husban/wife team actually) that prints maps of the whole Mex Riviera. These maps are fantastic and have lots of info on everything like places to eat and all the beaches and amenities.
The lady can be reached at email@example.com
Phil & Liz