Bertie It varies. I last did a Sydney trip in November, Others do one every couple of months. Sydney is not the only long trip, though it is currently the longest. Some of the Caribbean and Cape Town trips can be up to a week long. Long trips may be the exception, but they are very much part of a long-haul operation. If you are seriously concerned about the effect they'll have on your family life (which is understandable), perhaps you'd be better looking elsewhere?
What Goes Up Your questions have been dealt with earlier on this thread. You might have done us the courtesy of reading it before you asked.
Icing People do not leave Virgin except when forced to by events such as 9/11. In eight years, my seniority has risen by maybe 10 or 12 places. That accounts for deaths, retirements, permanent sickness victims and leavers.