Drupal 6.x

I have main website ABC.com with 5 subdomains on Drupal 6.2

The problems I'm facing are bellow:
1 - It is difficult for user content to migrate across the subdomains.

Detail: There are tabs on the top of USER PROFILE page for "My Content" and "My Images".
I was hoping that title links for all pages written by that user from all of the subdomains could be listed in that area
And also that all images from all subdomains uploaded by that user could go under "my images".

2 - Every time a change is made to the structure of the (site, taxonomy, blocks, configurations etc) the change has to be made on all 5 subdomains.currently we are doning indevidually.
Detail: Ideally, most of the administrative tasks should be implemented in a single change.
Things like content types, meta tag and post settings, taxonomy.
The structure of pages under site building, site configuration, user permissions.
All the things that make a site consistent in its look and function.

MAIN WEBSITE - http://ABC.com
SUB DOMAIN 1 - http://one.ABC.com
SUB DOMAIN 2 - http://two.ABC.com
SUB DOMAIN 3 - http://three.ABC.com
SUB DOMAIN 4 - http://four.ABC.com
SUB DOMAIN 5 - http://five.ABC.com

Database Structure:
There is only 1 database for MAIN site plus all 5 Subdomain with total 700+ tables.
Around 10 tables are shared in
MIAN website ie(ABC.com) tables doesnt' have any db_prefix

Upgrading from 5 to 6, I lost the book review module. (https://drupal.org/project/bookreview) I also lost all the book reviews. Oh, they're still in the database but they aren't showing up. When I try to edit one, this is the error message:

warning: call_user_func_array() expects parameter 1 to be a valid callback, function 'bookreview_node_form' not found or invalid function name in /home/novelspot/www/www/includes/form.inc on line 382.

Any suggestions how to get the book reviews back?

Hello,
I just start to work with Drupal, on a 4 years old website who never were updated and don't have a backup.

I need to do a backup, but I really don't know how.
Can someone please explain me how can I do it (with simple linguage) because I'm lost. I already see a lot of pages which explain how can I do it but there is so much language that I don't understand that I'm lost and I don't know how to do it.

Does Bartik template work in 6.28 version? I know it is core of 7.x but was just wondering if it works in 6.28.

The idea is to try working on sub-theme tutorial written by Carolyn on Drupal 6.28. I have seen customization tutorial for Garland theme but want to try Bartik.

I am looking for an experience Drupal Developer. Please reply to this message if you are interested.

Title: Drupal Developer
Location: Washington, DC

Can I do a backup with the backup and migrate modulo 6.x-2.7 of this link:

https://drupal.org/project/backup_migrate

even if the Drupal Core of my website is Drupal 6.10 and the Administration menu is 6.x-3.0-alpha3?

Thanks