Good thinking, Andrey. Leicas are much more durable than Bessas, they are that rare thing, a legend that actually lives up to its reputation.

Do some bodies have "Pentax Spotmatic" type metering? Literal answer no, because the Pentax Spotmatic had integrative (non-weighted) whole-field metering. Leica M6 has match-needle spot metering, some like this, I can't see the point apart from compactness, M7 has the extra of aperture-priority auto exposure, which I regard as worthwhile.

Your preferences will of course determine which viewfinder magnification is ideal, personally I don't find supplementary viewfinders a problem, I have Leica M2 but can't see the full 35 mm frame with my glasses on. I spent a long time working with screw-mount Leicas in my youth, so extra finders don't bug me. Big fast lenses - that's what Leicas are about, any model works well with these.

A Leica will need an overhaul every 10 years ONLY if used very hard, otherwise it will go 30 to 40 years. Most nice-condition older-model Leicas that you can buy today have been lying around unused for a while and will need a CLA, after which they will probably not need another in your lifetime. The Leica cloth shutter is a very old-fashioned design but is very reliable - I know of no particular problems (aside from needing to take care when changing lenses with older models in bright light - this is partly due simply to the rangefinder camera desgin, with no shielding mirror). Older Leicas might also need to have rangefinder prisms re-silvered, otherwise they can be hard to focus.

Is there a website with comparisons? Very probably, but the Leica Pocket book is not expensive and gives valuable info: