Is it possible to link / sync lead information of Marketo's list (or Smart List) with Google Spreadsheet and export it to Google Spreadsheet?
Yes, via webhook. You can push directly to a Sheet as shown in Logging Marketo form fills to a Google Sheet or can update the Sheet via an intermediate webhook gateway (which can apply more intelligence if necessary).
Also, if you rewrite information on Google spreadsheets, is it possible to synchronize them with Marketo?
Depends on what you want to do.
You can easily update lead fields via a webhook, if the lead already exists in the sheet in some fashion. Just look up in the Sheet and pass back the result. This is something we do often to enrich leads.
But you can't create new leads via webhook. You have to pull the sheet down into a CSV and import it, or use another method to integrate the platforms.