Airbus Girl most of this has been covered before on previous Virgin threads (there have been many!); you may like to do a search for more detail, but I'll give some basics here.
The initial basic pay for a Virgin FO is just under 42K pa from July '04. Hourly profit-related and productivity pay will add a further 7.7k (taxable & pensionable) assuming contract hours (750) are achieved. Subsistence allowances (not taxed) will add a further 5 to 7K, but that is not paid with salary. Take home pay will depend on your tax status and the amount you elect to contribute to your pension (the company contributes 15% as long as you contribute 6%+).
Rosters depend on the aircraft type; the 744 flies shorter trips (generally), and so pilots will average about 4.5 trips a month, the A340 peeps about 4. Days off monthly (at home) will be around 10-12 (but a lot of that will be spent sleeping!).
The leave system is about to change, so any comment is likely to be overtaken by events. Days off (and specific flights) can be requested two months ahead.
Benefits are similar to most major UK airlines: loss-of-licence, death-in-service, permanent health (critical illness), private medical cover, staff travel, discount schemes within and outside Virgin Group companies etc, etc.
There are lots of ex-RAF (and Navy and Army) pilots.
Very few leave Virgin, with the obvious exception of those forced to after 9/11. Most of those came back subsequently. Most pilots see Virgin as a permanent career move, not a step to anywhere else.