Is it at all possible to create a link in SFDC1 which will open the Safari browser and go to a specific VF page? Or even just go to the SFDC login page?
Unfortunately it appears that there is no way to achieve this. In theory, given that Salesforce1 is built on top of the mobile sdk, which in turn sits on top of cordova, we should be able to open a link in the web view, child browser or device browser (e.g. the external Safari browser on iOS), according to the cordova docs:
var ref = window.open(url, target, options);
target: The target in which to load the URL, an optional parameter that defaults to _self. (String)
_self: Opens in the Cordova WebView if the URL is in the white list, otherwise it opens in the InAppBrowser.
_blank: Opens in the InAppBrowser.
_system: Opens in the system's web browser.
However, attempting to use this mechanism with the _system target still opens the child browser. As far as I'm aware this is due to the cordova configuration (which gives some additional control over this) that is part of the installed application and therefore not available to us to change.