I'm not sure I understand why you would need to go to the extremes you're describing.
For architectural shots, you need:
1. Good wide-angle lens, with the ability to be sharp from edge to edge;
2. Solid tripod
3. Clear Field of View for composing the image
4. Good lighting
Of course, these are all variables. You could scrimp on the lens, if the lighting is perfect, etc.
I don't think bulb mode is necessary. I've gotten some reasonable shots with far shorter exposures than bulb mode would indicate. Usually, I've worked in Av, and let the aperture value set the shutter speed.
What is important, I think, is to use your best aperture - f22 and up. This will ensure as much as possible that you have everything in focus for your full depth of field.
The tripod is mandatory to me. Because an f22 or up is going to cause a fairly slow shutter speed, and shake could become an issue. At that point, maybe mirror lock-up will help. I've never used it, so I can't comment.
Just my .02 cents, I don't claim to be an expert
. I just like taking building shots.
Ian Mc.