How Long....? And other voyage questions.

I know that my grandmother's parents and her 3 older brothers were on the ship Angelo, departing Christiana on July 18, 1879. What I would like some help on, are the following questions: 1) How long would the voyage have taken from Christiana to Hull? 2) Once in Hull, how long would they most likely have been there? 3) Would they have most likely left England from Liverpool or some other port? 4) What is the best way to find out what ship they booked passage on from England to America? Thanks