Plating depends on what I am serving and how formal it is, I have to say my preference for a small group, 8 or under, is certainly not to, as the food always promotes conversation as people serve themselves/are served and I have bought so much pretty serving ware that I like to show it off, lol.
Yes, seat people first, definitely..so they settle. I remember giglgling rudely but pretty much uncontrolably, partly with nerves, at a dinner party where we started with borsch, as everyone sat down trying not to disturb the bowls of pure dye onto the table or the carpet below....inevitably somebody failed....women need time to find somewhere to stow their handbags if they have brought them to the table, (why are so women afraid to leave their purses/bags on friends'sofas?) and its awkward to be one of the first seated oer a tempting plate of even cold food if some people are taking ages to get seated!