I would like to run GLMM for model but I am not strongly familiar with R. Could anyone help in terms of

1. choose the best family model, i.e. binomial, poisson, beta... etc?

2. choose the best model, i.e. y~a+b+a*b

3. code to run GLMM in R

4. code to run post-hoc GLMM in R

Any examples will be help to me.

Thank you.