I do not see why you cant use my current version for your not webaccessible storage. Isnt the point that you hide the colums with direct link and hotlink urls?
Your second point I also dont get. What do you mean? LUM_Attachment is the table names created by the attachment add on, and LUM_User is created by vanilla. these should work out of the box..
$Configuration['DATABASE_TABLE_PREFIX'] = 'LUM_';
however i have no Files tab (not sure if i'm supposed to have one?