jth-3673R!!!
I used to frequent Lotus Talk. It was nice but they really cater to the newer cars. I think it's good that you landed here! We love hearing about, helping with, and watching the progress of project and you have got yourself a project!
I can't really tell but I suspect you'll be able to fix the door. If you're unfamiliar with doing fiberglass work, it's pretty easy. Hell, even I did a bunch on my car and it hasn't fallen off yet! When you get the door off, post some pictures so we can see for sure. It's almost always possible.
I think you're going about it the right way. Spyder makes a great frame with some cool add-on bits like rear A-arm suspension!
Lastly, I second JB's suggestion to look into a Zetec swap. Not that I have anything against the twin cam motor, but there are a lot of options with the Zetec and they are relatively inexpensive. Lots of people have done that swap so you'll be able to get lots of help. Also, rebuilding a TC is not an inexpensive proposition.
Glad you made it here! We're all waiting for future progress reports... AND PICTURES!!