hello everyone
i'm new here so i hope i have put this in the right place!

ok, right i have a booked connecting flight from london to new york and then vegas and i have a few questions please (as i have never done a connecting flight before) thanks so much in advance!

ok so the flights are with the same airline the whole way- delta

1. do i need to collect my bags - or will they simply be transported from a-b
2. will i have to go through passport control to get to the next terminal?
3. i have to get to jfk terminal 4 to jfk terminal 2 - how long does this take rufly - is this simple and is it free to travel between terminals?
4. will 2.15 hours be enough to transfer all ok?

will i need to know anything else that you might think is useful !

again thanks for your help its much appreciated!