Here's my difficulty... I've been using Movable Type since way back in the dark ages - I believe 1.2 or something like that. And I've always had my own custom templates that I've upgraded from time to time when I've upgraded my installation.
In the past, one could download a default set of templates, which I would open next to my own templates and copy in chunks of code, etc. Now I can't find a default set to download to my hard drive and open up -- everything seems to be the "auto install" type that comes with the style library. I certainly don't want that - I want some flat text files I can open up, not anything that screws my current templates up.
Also - plug-ins. I can't find a list of the default plug-ins that come with a new install of 4.1. I'm sure I have plug-ins in my directory that aren't compatible from ones I've tried over the years. Also, I at one time installed Byrne Reese's plug-in manager, and it never worked and totally screwed my plug-in directory so I couldn't take anything in or out. I finally am able to delete plug-ins, and want to compare what I have installed with a list of standards, but I've been hunting around on Movable Type's documentation and have yet to find a standard list.
Any help at all would be much appreciated.

The flattened templates may be what you're looking for:
http://www.movabletype.org/documentation/designer/mt4-main-index-default-template-flattened.html
Great question, electrasteph. Michelle's outlined some of the template documentation that helps answer your initial request, but we've got more on the way.
As far as the list of plugins goes, you definitely caught an omission in the current documentation, so good news: I made a list of what's in the package in MT4, based on your question. Hope that helps!
And thanks so much for being part of the MT community for so long. :)
I keep getting a permission denied message when I try to post a new topic so I'm testing to see if I can respond to a message but not start new topics.
Michelle - your permissions have been adjusted on this blog and you should be able to post and comment fine.
Steph, you have a great MT resource right down the street. You know I've been working with MT 4 for months now and I'd be more than happy to help you out. Let's get together for lunch or something and I can help you with anything you need.