[Dovecot] Homedir vs locations vs mail_location?

[Alexander Chekalin]

Hello,

I use Dovecot for rather long time, but I'm still in doubt for some 
small things. Here they are:

1. The homedir value points to the place where everything for the user 
stored at, while mail_location is something (some place) where mail 
stored at. if I deal with pure virtual users (all users are in sql 
tables and no system homes for them at all), should I ever care for 
returning meaningful value for 'homedir' (via password_query's 
userdb_home), or I can simple return empty or constant ('' or '123') for 
it and it won't mess anything?

2. If I use single (default) namespace, should I set namespace's 
location (to the same value as global mail_location), and should I 
expect anything strange if I skip it to set? Reversely, is it possible 
not to set global mail_location and set only namespace's location (which 
would be more logical as namespace definition is compact and easy to 
find in config)?

I've reread my questions and see it is dummy ones, but I'd like to know 
that for sure.

Thank you in advance,
   Alexander