Carnival Half Moon Cay clamshells and drink package

[nklpikl]

I've search the boards and see conflicting answers. Mostly because it seems Carnival and HAL do it different.

How do you rent a clamshell? Is it on board at excursions desk or when you get onthe beach at HMC? Also how much are they?

Is there a drink package just for HMC? My research shows it may only be available if you are on HAL? 

[ilovethesparkles]

Does Carnival offer this drink package fro HMC? If so, where and when do we purchase it?