Do you like smoked salmon and caviar? And can mayo stay out of fridge for around 4 hours?

I am preparing an appetizer for a party with smoked salmon, caviar and mayonnaise. In Europe these are regularly eaten for fancy parties, would you be grossed out if eating caviar -fish eggs? Also the party is at 12 and I will be making the appetizer at 8 can it stay out of the fridge all this time if there is no room in the fridge?