You can just try to install over the top of it, but generally that doesn't always work as well as getting rid of it first.
For all of your saved things - log into chrome before you blow away your installation.
If you log into Chrome, it will save all of your bookmarks/etc. in your account. Then, anytime you log into chrome from anywhere else (another computer, for example) all your stuff will be there. I love Chrome for this. My office, my home desktop, laptop, Nexus 10, and Galaxy S3 are all sync'd with the same bookmarks everywhere. I can bookmark something at my desk, and go back and check it out later at home on one of my other devices.