You'll be a lot more comfortable if you read up a bit on how rangefinder cameras operate and how they're different from SLRs. I'm not sure the best place to tell you, though.
[Hey, gang, maybe this is a hint: We should collaborate and write up a "Rangefinder Camera 101"-type document to help first-timers figure out what they're seeing through the finder, why it always looks in focus, what those white lines and the little rectangle in the center are for, etc.]
So, let us work on that. Meanwhile, a couple of quick answers:
-- You won't have any problem
using a 25mm lens or focusing it accurately. On an RF camera, using the rangefinder is completely independent of using the viewfinder, except that you look at them through the same eyepiece -- the rangefinder is always equally accurate no matter what lens you put on.
As you note, though, the widest frameline is 40mm, which isn't as wide as your lens -- so you won't
see as much through the viewfinder as you'll get in the picture. Normally the fix for this is to buy a little 25mm auxiliary viewfinder that goes in the accessory shoe on the camera top. The auxiliary finder shows the same field of view as a 25mm lens, so you'll be able to predict what's in the picture more accurately.
Yeah, having to have a separate viewfinder for every wide-angle lens is kind of a nuisance, but it's got some advantages, too, such as the fact that the view is super-bright and clear. And if you want to size up picture-taking angles without looking like a geek by walking around with a camera up to your eye, you can slide off the finder, carry it in your hand, and look through it to preview possible shots, the way movie directors do.
-- It's possible for a rangefinder to go out of alignment, just as it's possible for the focusing screen or reflex mirror on an SLR to go out of alignment. This is more likely to happen if the camera gets banged around a lot or is subjected to intense vibration. You'll read a lot on this site from people who have had them go out of alignment. That's really an exception, though -- most people have no problems with this.
If you want to verify it before an important picture-taking session, an easy quick check is to set the lens to infinity focus and look through the rangefinder at something with strong vertical lines, such as a TV tower, that's at least six blocks away (preferably more.) If the vertical lines in the rangefinder patch line up correctly at infinity, the rangefinder should be fine for closer distances too.
If it ever does go out, CameraQuest will realign it for you as long as your camera is under warranty. If it happens after the warranty expires, it's still inexpensive to fix -- Cosina designed in an external adjustment port (under the accessory shoe) so an "in-the-know" repair technician can touch up the RF in a couple of minutes.
-- Shutter noise: Your Elan 7 is a pretty quiet camera; you may think the Bessa sounds a little "sharper." That's mostly because the body is smaller, so there's less bulk to absorb the sound of the shutter. However, because the Bessa has fewer moving parts, the noise it makes doesn't last as long as the noise an SLR makes.
Any camera will be audible in very quiet situations, and what kind of noise is "intrusive" is very much a matter of personal perception: one person may find a Bessa really distracting and not notice an Elan at all, while with the next person it may be the other way around. I don't think it's a big thing to worry about.
Be sure to come back and ask more questions if you want to know more about your camera or about rangefinder photography in general. There's a lot of good info on the CameraQuest website too. Good luck, and welcome!
