A few questions about bazaar and/or mercurial on dreamhost

So I installed redmine using passenger, seems to be working fine. Now I naturally want to had a repository to my project.
Bazaar or mercurial would do it. I installed bazaar on my account long ago, so I guess I could take advantage of that.

Say I would go for mercurial, would i ave to install mercurial on my acount on dreamhost?

Another thing that confuses me is the user administration. I’ve used bazaar and mercurial for my own personal version control needs, but I’m not famliar with their multi-user support.

Do they rely on server level user administration or do they have their own user set?

How does redmine integrate with bazaar (or mercurial) are redmine users connected associated with bazaar(or mercurial) users?