1) We have few devs, where some of them have few own plugins (e.g. I have Facebook), but most of plugins doesn't have dedicated developer.
But anyone interested could fix/improve any plugin. TabSRMM's dev Nightwish (which owns that website you mentioned) stopped development even before NG was created.
And all actual/updated info, related to NG, is on our wiki. So all other websites (of particular plugins) are not related to NG and are not up to date.
2) That's not a good idea, as combining old and new versions of plugins/core will result in weird problems or crashes sooner or later. But yes, you can lock plugin from updating, but it's discouraged.
You should rather make bug report to our
tracker so it won't get lost here on forum, and someone may eventually look at it.
If it is problem like this, where you know it got broken in some version or in some particular time, then it's good, because you can try different releases from different revisions and narrow down where exactly the problem started to happen.
a) you can either compile the revisions yourself, but that require more knowledge and time or
b) you can tell someone in our jabber conference to help you identify potentially problematic revisions (which affects TabSRMM source code) and then ask Watcher to compile these revisions for you.
Then you can try to reproduce your problem in each of them and find out when it got broken.
With that info you it's easy to reach out the developer who commited the broken commit and ask him to look at it.
Note to some wiki author: Maybe this info should be (re)written to the "reporting bugs" page to better understand the process for users in these cases?