Hi,
It is generally better to post different questions in separate posts. Also, if you can include some non-sensitive example data as a .jmp file attachment that really helps people in the community to help you.
On your first question, I think this is hard to answer without knowing more about what you are trying to model. I think it would be unusual to have a covariate as a random effect but there might be a reason for doing this.
I assume that you have other effects that you are modelling as random, otherwise you shouldn't need to use the GLMM add-in. There is a "Generalized Linear Model" personality in Fit Model for Poisson and other distributions. There is also the Generalized Regression personality in Fit Model in JMP Pro.
I hope that helps,
Phil