My DS Daniel is 4 years old turning 5 in April.
He can dress himself,do up and undo buttons,usually put shoes on the right feet.
He can use a knife and a fork but usually just needs a fork as I tend to cut up his meat just to make dinnertime a bit quicker and easier.
He is very fussy with what he eats but he will eat most things I put in front of him especially if he wants dessert.

He can put on his own seatbelt most times, he has a bit of trouble when sitting in the front part as we have 1 baby seat and 2 boosters and not a lot of room but if he is in the back part then he doesn't have a problem as there is more room for now.
I wouldn't worry about what anyone else says or thinks, he sounds like your typical 4 year old boy and each child is different.Some children can talk better than others at the same age, some are more independent than others, the list goes on.
I hope you have a lovely stressfree holiday and you have a good time.
Good luck
Michelle