1. You should not have any problems with the BESADMIN in another OU than the default user group.
Dilemma 1: do not delete the user, but just simply move it to the user folder. No harm will be done.
Dilemma 2: why do you want it not te be a member of the domain users group? See first remark.
Dilemma b: the SQL DB and the configuration database are the same. Just another name for the same SQL or MSDE database.
last question: You can simply give the BESADMIN account SA (system administrator) permission on the SQL server instance.
I do not know of any setup.ini file which needs to be edited. You can savely ignore it, as I have done installations more then 50 times without doing it.
BlackBerry consultant @ dahvo