[support] Upgrading Drupal

[Daniel Carrera]

Hello,

I'm going to be upgrading Drupal in the coming weeks. I have a few 
starter questions:

- I have version 4.7. Should I upgrade to Drupal 5 or 6?

- I have two other minor sites that also use Drupal. They are small and 
have few or zero plugins. Would it be a smart idea to use the multi-site 
feature and put all three sites in one place or should I have them 
separate? In other words, would multi-site make upgrades more 
complicated in the future?

I'll have to fix many issues with plugins as I upgrade.

* In the current site I put all the plugins in the global plugins 
directory because I didn't know better. In the new site I'll put them in 
the site-specific directory.

* I have a lot of plugins. Several don't work well and I would like to 
get rid of them if it's at all possible. I wonder if getting rid of 
plugins and their associated data may turn out to be a problem. 
Especially if the plugins in question are not available in future versions.

What is the best course of action regarding plugins that may not be 
available in the recent Drupal versions?

Thank you for your help.

Daniel.