I have not been able to figure these out, although I have searched both the online manual and the forums (probably missed it):
- Edit metadata screen keyboard shortcuts: when you are on the edit metadata screen, what keyboard shortcuts do you use to the different fields? There are underlined letters for most of these fields. Clearly they must represent shortcuts, but trying these with /without Shift, Ctrl or Alt did not work for me. The answer is likely obvious yet I can't see it. I am running Windows 7.
Alt+letter works for me on W7. do not there is more than 1 'd' and on W7 you must repeat to get to Date (I tend to use Tab, myself)
- GUI-based AND tag queries: is there a simple way using the GUI to build tag-based queries that are linked with ANDs rather than ORs? For speed purposes, right now I build a tag query with mouse/ left hand column, then modify/ add the search string by typing.
At the bottom:Alter Tag Browser: Search type: Match All
- Add books without tags: I looked through the preferences options but could not find how to strip tags so that added books come with no tags. Yet, many posters refer to the fact that they are doing it. Not sure where the feature is? My calibre version is up to date (1.35). Right now, I
add a batch of books, then I select the books I added,
edit global metadata, and
remove all tags.
On the Edit metadata or Download Metadata or Preferences: Configure metadata download . Remove the Tick next to Tag for ALL sources or select a source and click the 'Configure Selected source' button and set by source 
- Lessons learned on virtual libraries: any tips on the best ways to use virtual libraries? I don't mean "how to", that's simple enough - I mean lessons from experience. (btw I learned a lot from unboggling in his thread "how I manage ebooks with calibre")
- Read/ unread: based on experience, what are the pros and cons of the two methods mentioned in the forum, e.g. READ tag and custom yes/no column?
IMHO Using the Custom column does not get lost in the Tag clutter, it is a separate field
Many thanks in advance. I really appreciate everyone's help. I will be sure to contribute answers when I know more:-)