Gmail and Chrome Identities - What's the relationship?

I have just gotten use to having all my Google identities merged whether I like it or not. My gmail, Google Docs, analytics, Youtube, blogger, adsense, adwords, and Double-click identities are all merged.  I have even accepted the loss of my old favorite homepage, by Google homepage by now keeping bookmarks on my Chromebrowser and a backup copy in a google doc.

But I'm now confused by a new pair of related but distinct Google-owned identities:  Chrome and Gmail.   Sometimes, I'm on a computer and all my bookmarks are there in the Chrome browser. Sometime they are not, I've never really figured out why or how.

Now I have a real problem that I'm trying to figure out.

I was traveling and used Gmail on a borrowed computer. I even carefully copy-pasted in parts of my password to protect against potential keyboard recorders. After I logged out, my email account remains on the Chrome browser that I used which is annoying but not much of a problem. But, somehow, all my Chrome bookmarks remain on the browser. Since I have some confidential URLs that are the management tools for some of my sites, I'd like to remove them but I can't see how.

1. Can anyone explain how logging in with my Google account automatically brought my Chrome bookmarks onto the borrowed computer?  Or, did I do something that I don't remember.

2.  How do I remove a Chrome profile from a computer. It's the Chrome browser on a Mac.