From what I've read here, pineapples need a well draining soil. With that in mind, would the gritty mix be a better choice or would the 5-1-1? I have both, so that will not be the issue?
I'd go for the Gritty Mix, since the Pineapple will be in the mix for several years.
Also, the Gritty Mix will provide more suitable drainage during the cool Winter months.
Do I use the gypsum in conjunction with the gritty?
Yes, you do use Gypsum.
However, if you're using a fertilizer that contains Calcium and other micro-nutrients,
then you can omit the Gypsum.