I would like to configure my MediaWiki in this way:
while creating an
account the user need to fill *all* items (username, password and
e-mail). Then he/she must confirm it from e-mail account. Then he/she
can login and edit pages on wiki...
I think there's a minimum password length setting, set that to more
than 0 to require a password. If you can't find such a setting in
LocalSettings.php, look for it in includes/DefaultSettings.php and
copy it across.
You can require emails by setting $wgGroupPermissions['user']['edit']
to false, and $wgGroupPermissions['emailconfirmed']['edit'] to true.
(I think those are right - just make sure they look like the existing
settings in LocalSettings.php.)