Frequent root tasks under user - and on remote hosts

Not that I'm very tired of typing my root password a hundred times a day, I just can't see any security in that. People are using things like sudo and calife. I want something like ssh-agent/ssh-add: type my root password somewhere after I login as user, then type "root@ echo 123" - and voila! After some time of inactivity, or after reboot or a special command - I lose the power to impersonate root.

I want more - intelligence. If I have the root@ power, I want to be able to anyuser@. If I don't I want to be able to get the credentials for anyuser@ (by typing their passwords or easier - by using ssh keys). Hmm, how do I get an idea through a parenthesis... So why don't I really use ssh keys for that. True, some hacking lies ahead to bind it all to ssh-agent, but it's possible. Moreover, I want to be able to anyuser@anyhost (including root@anyhost which should go through current_local_user@anyhost) - that could be possible with ssh keys.

If my environment gets notion of local/remote mounts and how they match, it would be cool if some I/O-hungry tasks could be run remotely automatically. E.g. I have lot's of music mounted via NFS - a converter program should run remotely if started inside the mounted directory tree and installed on the remote host.