We usually raid at 19:00-23:00 server time. As most people came back from vacations we continued 25-men, so Kara(badge runs) and ZA will be held mostly on weekends from now on. Raids are usualy set during the week 4-5 days a week(one day free for family busyness/real life xD) .
The requirements for DPS classes are strict. ~1000 spell damage bonus and 25% crit are minimum.
That's what i think. I'm not an officer, but hope this helps.