Fozzie:
1) No. 1 point per work unit.
2) Yes, go to lifemapper.org and sign in. You can choose species, geography and favorite data source. Be aware that unassigning yourself frequently doesn't work, and you may be stuck doing the same work unit hundreds or thousands of times. The more general your preferences, the more species you'll get.
3) Twice a day, at 3 AM and 3 PM Central Time (US) (GMT-6)
4) It varies. I figure on a rough average of 15 minutes per unit, but it depends on the unit - some have more data points than others.