Does anyone have the link for the latest version of the MSI package (mentioned in the October 2015 Release Notes) on the salesforce AppExchange?
You'll be able to find it in the MSI installation instructions, but I do not believe that the updated package will be available until release day on the 23rd.
It's a managed package and therefore is supposed to update itself on your salesforce instance.
The version 1.4343.0 that is apparently on the app exchange is salesforce1 compatible, so it seems to be the new one.
You can install it on top of your previous MSI installation, it will simply upgrade.