one thing that I see a lot of people looking at is the ability to change the zone from open pvp to safe... this is the war server for a reason. Something that hasn't been voiced is keeping the control totems available for destruction at any time. to that point though the destruction of a totem should take an extended amount of time or be under "duress" for a period of 24 hours. If you made it were it took an hour to create the control totem and then another 24 hours to be able to build or terraform the area. and only having 1 totem in que to be built at a time and only receiving the control of an area upon having 4 control totem up. It would open for a very entertaining objective. The lower danger areas wouldn't be messed with as often and the more prized areas would be a warzone of chaos. as for the minimum area a control point has I think 100m would be ok, 50 is just a bit too small and really too easy to get into no matter how its built. A high resource cost for upkeep is a must as well and should scale as the totems increase, also to that point I don't think there should be a capped number of totems as long as you could afford it I think any tribe should be able to set as many as they like this makes for a good defensive strategy as well as a good "gold dump".
I could care less the tribe size minimum, if you want to be an army of one you better be a bad a**.