Hi Claire,
We were there a few weeks ago. Light charging with adaptor is ok (If the hotel runs out of power/electricity like we had you can always charge it at the shop).
I used a 100gr Bare undersuit which was more than enough for 1-2 hour dives. For longer dives I would probably take my Weezle because of weight and it's easy to dry/wash. No gloves but I did use a cap which made a big difference. Make sure you also bring goed underware to remove the sweat from your body! It's going to be really warm before you enter the water. watertemp: appr 25 degrees. And don't forget the reppelent
If you have any more questions, let me know.
Enjoy Mexico, you will absolutely love it and be addicted to that area!! Say hallo to Chris and Danny from me.
Anne-Marie