1. Less than a 1GB, currently.
3. There is a Mac Version of Wakfu, but I've heard there has been problems.
4. Astrub, the town that you start in, is really laggy especially when it's afternoon, evening, or the weekend in France. You should get really far away from it to have a better experience.
5. Well you have five character slots, enough to test almost half of them? ;;