Garage doors

Ahoy all, I’m looking for advice on making garage doors. This is a project I’m looking at down the road, maybe the next year or two. The doors would be conventional hinged doors (i.e., “carriage doors”), frame and panel construction. Each door is about 4′ wide x 6-1/2′ high. I’d like a couple rows of windows in the upper half of each. The problem plaguing carriage doors is that they often sag over time, which is why flip-up and roll-up garage doors superseded them. I need carriage doors, however, so I want to construct mine with strong joints and beefy framing members to avert sagging. I think that’s possible with a good design and careful work. I keep telling myself that there are lots of hand-built heavy doors in the Old World that are hundreds of years old and are still hanging just fine. (At least, I hope that’s true.)

I’ve been searching old carpentry and woodworking books for discussions of techniques for heavy doors, but I haven’t found much useful. Maybe I’m looking for the wrong key words; “carriage doors” seems like a modern term. I’ve found some sites online about making carriage doors, but they don’t offer much in the way of detailed or usable information. I have many questions. For instance:

1) What dimensions should the framing members be?
2) What’s the best material to use?
3) What joints to use? How best to make them?
4) Is diagonal bracing necessary, and, if so, how do you do it? (Is diagonal bracing called “bucking”?)
5) How are the windows incorporated into the design?
6) Any other considerations to be aware of?

Can anyone point me to some resources on this? Any books, websites, videos, etc.? Has anyone here made garage doors or other large, heavy doors and can offer some advice?

Thanks,
Craig