Tag System for Dolphin 7

my dolphin website is going to be largely based based on a tag system however, the current system does not seem to allow users to tag in tree system i want a system where users can upload/post to the dolphin provided ways to upload/post (Photos, Videos, Files, etc.) based on the type of content they are uploading and then have a structured tag system as well as the ability to add additional tags that are not currently available in the existing tag tree system for example: i want a user to be able to upload a document to Files and then tag that Document in Essays - Economics - Opinion and then to also be add the tag's wall street and timothy geithner or upload a photo and tag under (for a photographer) Photos - Artistic - Black and White and be able to add tags Italy Rome and Colosseum i also need a way to easily add/delete (basically manage) the currently available channels to tag from the admin site the users also need to be able to easily search through the tags, preferably at tags home where you choose what type of content you want to view from drop down menu's for example Essays - Economics then press search that brings up all publicly available posts/uploads tagged like that, also a feature to add into a regular search box before you search the ability to narrow down Essays - Economics by other user defined tags such as timothy and then search all Essays - Economics that are also tagged with timothy that are publicly available to clarify, when people tag things i want them to have to start from the top if using the tree tag system for example: to tag in economics they have to choose essays first, they they are given different tag topics from which they can choose economics from, they should not be able to tag straight to economics (unless i define that as a separate top of a tree) i hope i have been specific enough with this description, it is actually very simple in the things i want: a tree style tag system users can use to tag their content a way to easily search through tagged content a simple way for me to manage the tag system (add/delete tags and tag trees) from the admin website