Upgrading Drupal

I'm looking to move one of my sites to a different host that I have a 5.1 multisite install running on.

The site is currently on 4.7.2 so would I be best off upgrading step by step to 4.7.6 then to 5.0 and finally to 5.1 on the existing host before I move to the new host? Or could I move to the new host and shove the database directly into the 5.1 multisite?

Well. I've enabled all my available modules..

Yet it classifies the - latest-poll, latest-blog post .... module blocks as "Disabled"

Why is this ? How do I fix it ?
Troubleshooting please

Thanks in advance.

I have around 10 drupal sites sharing some databases:
'users' => 'compartides_', // usuaris
'sequences' => 'compartides_', // perquè hi hagi IDs únics
'sessions' => 'compartides_', // per compartir les validacions
'authmap' => 'compartides_', // npi de perquè
'locales_meta' => 'compartides_', // traduccions
'locales_source' => 'compartides_', // traduccions
'locales_target' => 'compartides_', // traduccions

It is not the same thing to upgrade 4 at 5 that update of 5 at 5.1.

Which the process should be to update from the version 5 to 5.1 ?
Because if I re write all my directories with the new version, I lose my modifications!

Please, describe the process step for step.

I just finished building up a Drupal 5.0 website. But I found out I can only upload files to content, which is defined as a node in Drupal. To be able to attach file to individual comment, I download the module comment_upload-5.x-1-dev.tar and unpack it into module folder with the name comment_upload. Unfortunately, I can not see any change when I open administer>>module, which supposed to have comment_upload module mentioned in installation manual. And same problem happened when I try to install nice_menu module. Could anybody help me with this issue? Thanks a lot!

After a user logs via /user/login then the next page states "Access denied You are not authorized to access this page." at the URL /user/admin and the admin menu doesn't appear.

This started after the upgrade to 5.1 from 5.0. Luckily I was logged during the upgrade but any further attempts to login fail.

Any information would be helpful.

Thanks!

The log states the following: