I like this idea except for the towering thing. While it may seem fun, it could be said that guilds should just go attack actual towers.
Maybe there could be a gralat fee to be able to upload your own levels.... which brings me to a new point.
With all of these advancements in making guilds better, members should be able to donate to the guild. Rather than the guild leader solely paying for furniture, levels, uploading graphics, etc. right out of his/her pocket, it would be helpful if members could donate gralats or furniture to a guild fund. This would probably also strengthen bonds between members and build loyalty --> if a member donates a lot to a guild, they probably won't want to leave. Also, if the guild point system gets implemented, points could be given per donation & for items bought towards the guild house.