QUESTION Part 1.
As far as I know, when you edit a symbol, it affects all instances of the symbol within the current document open. Is there a way to have the changes affect other documents? Illustrator doesn’t seem to let you import and save and update symbol libraries, as it just creates a new instance of the library when you open it in another doc.
QUESTION Part 2.
The main reason I ask is, I am wireframing a responsive site in Illustrator. I want to be able to have a document for each page. I.e home.ai (this will contain multiple artboards of the various responosive sizes of the home page). So when I make a change in home.ai in say the footer via a symbol, I want the footer symbol to also change in about.ai or contact.ai without me manually having to change it.
Is there a better way to do this?
No. Symbols and libraries are document independent, they do not “link” to other documents. In addition you can’t use linked images within symbols.
You will have to either duplicate symbols manually across documents, or used linked files and forget about using symbols. Just create a file that is “footer.ai” and use
File > Place to place a linked version of the file. If you edit “footer.ai” the link will update when you open any document containing that linked image.
In this instance it sounds as if Symbols may not be what you need.
Of note is that Adobe CC2014 has a shared library panel that connects to your Adobe account. But this only places things like Symbols within easy reach. In order to use these items in a document, they are copied to the document itself, not linked. You’ll note that if you click one of these CC library items, it appears in the appropriate document panel for that item rather than staying independent. This common CC library manger is merely to allow you to access library items from a common location, but you can’t actually use those items from that panel.