Couple of questions here:

1.) What OS version began releasing patches/feature updates through Windows Update during the Beta/RC stages? Is there a place I can obtain these offline updates since the older OS's cannot receive them automatically anymore from Microsoft?

2.) Is there an complete list of updates for past Windows non-RTM releases?

It was easy to locate all the Windows 8 CP/RP updates using the WSUS script, but older releases like Win 7 Beta/RC aren't as easy to search for. If this makes no sense, I can try to clarify. Any help is greatly appreciated.

Thanks!

AFAIK Windows 8 is the first such OS, though Windows 7 may also had updates during development released through WU...

A significant one was the MP3 Update during Beta (Build 7000)

Thanks for the answers guys...it would seem most of the updates can be easily found by setting up the Windows version search filters on Microsoft's website and sorting those results by date. Honestly didn't think Microsoft would make those updates accessible. Glad I was wrong though.

Thanks