I don't know how the selection process works, in my last place of work one of my colleagues had done jury service 3 times yet I've never been called up, my father did jury service but he wasn't allowed to talk about the case until the trial was over.
The selection process is completely random, which is why some people have been called several times and others not at all. I think people are chosen from the Electoral Roll.
I did jury service about ten years ago. It was a bit of a shock to be wheeled into the court, get sworn in and then discover that we were hearing a murder trial
The guy didn't deny the killing (it was his one-time girlfriend) but his counsel was trying to persuade us that it was manslaughter, not murder.
Quite a bit of the evidence - and of the judge's summing-up - revolved around defining the difference between the two offences but the photos of the victim were pretty gruesome, as was the murder weapon, and I wouldn't want to do it again any time soon. We found him guilty of murder: one of the other jurors was an ex-colleague of mine and she suggested to everyone that, as I worked in HR, I was used to giving people bad news (which was true, sadly) so I ought to be the Foreman. It's quite heavy, telling someone to their face that you have found them guilty of murder......
I seem to recall that we were told we shouldn't discuss the case with anyone else (except other jurors, obviously) whilst it was being heard, and that we shouldn't discuss the detailed deliberations that we went through as a jury at any time, then or thereafter.
Whilst I'm in no hurry to repeat the experience, if called I would do it again: it's our duty as citizens and, in the great scheme of things, it's usually just a few days out of your life.