How should one behave at dinner with stagers?

Question

and how should one drees?

Answer 1

depends on the situation, but act nicely

Answer 2

Be polite, be friendly, don't act too loud, no burping, or farting at the table. When you eat you work from the outside-in, ie if there are two sets of knives and forks, you use the ones outermost first. Dress smart-casual, if you don't know where you are going, don't wear jeans or denim, some places won't allow you in if you do.