DO is the director of operations, who runs the day-to-day show.
Pay has changed since I left. It used to be $60/day starting, but it's gone up some. If you go to their website, look under employment. There's a FAQ that explains it better.
You'll fly Mon through Fri, except banking holidays, so this is a full time job. In theory, pilots bid for a run every three months, and fly that run until the next bid. Depending on your seniority, you can fly a particular run for as long as you can hold it (I once held a run for something like 8 months). As a newhire, you'll be switching runs quiet a bit as more senior pilot leave and more desirable runs become available. Some runs have late starts and early finishes (they usually go senior), while some have early starts and late finishes (usually very junior). So the hours you work will depend on the run you get. If you want to make extra money, look for a job that lets you work weekends and, when seniority allows, mornings. Keep in mind that your job at RAF needs to come first. If you miss work because of a conflict at another job, you'll get the boot and you don't want that on your employment history.
As a cop, consider going part-time and working weekends if they let you.
First, though, you'll need to get your hours up and get a multi. They only hire if you have the Part 135 IFR mins, or if you're within 10 hours or so. A multi rating is also a must.
Overall a good place to work and cut your teeth getting some real flying expriences.