Yes members can be reactivated. However, this reactivated members would be treated as a new members and we would only use the points they've earned after they've reactivated again. All of their previous points will be lost.

Regarding the points, whenever a member is deactivated, thier remaining points are adjusted and thats the reason you are seeing the same +ve and -ve numbers in two different columns. The key here is the ActivityDate and everytransaction is attached to it.