How and where can we request new WordPress hooks to be added?

I use the great Changelogger plugin, which adds plugin version history to the plugins page when there is an update. Although I would like it to, it doesn’t work from the updates page where you can update WordPress core, plugins, and themes.

How and where can a new hook for that page be requested so that the changelogs can be added to that page too?

You’ll want to make a new ticket here: http://core.trac.wordpress.org/

Explain why you want a new hook and how it could be used. Including a patch file also goes a long ways towards getting the hook included in WordPress.