Do i have to add 30 minutes of ads to the movie time for the ending time ...i.e if it says the movie is 2hrs 15 minutes it is 2hrs 45??

Closer to 20 but yea

Usually 15 minutes of trailers are added to the beginning of every feature depending on how the studio wants you building the trailer pack. The end credits are taken into account when determining a features length. So only an additional unplanned 15 mins, which begins when the films time is posted. I.e a film posted as starting at 6 will actually start its feature at 615.