The problem with "approximately" is that over long periods of time (e.g. trying to hatch an egg) small differences in accuracy can make a huge difference.
I think the idea is that the person who has the original tag is able to create sub-teams and therefore the only people allowed to use the tag have to go through some sort of hierachy
I do agree with this to an extent, but I'm not so sure that the tag is necessarily as powerful as the clan name in terms of reputation. People would certainly be able to distinguish between the lower ranks of a clan and the most "notorious" section of it, I'm sure.
I do completely agree with this. A single tag, such as KoG, should be able to have numerous drop-downs with the same tag, under different names. It could also be integrated with promotions/demotions into separate clans under the same tag, which would certainly spice things up a little.