This is opening a huge area for discussion - the relationship of monochrome Leicas to large format film is.... complicated. Have an M10M, and use it as a traveling "fine art" camera, sort of a handholdable tool to get high quality BW files, highly pliable, in unusual situations as the high ISO capabilities are exceptional.
Would this compare well to LF? No, I don't think so. There are so many many differences, its almost too much to cover. But to answer your questions:
1) hardware by the M240 and on is really solid. No issues. There is the occasional electronic hiccup requiring a restart, worst case pull the battery, but these are now rare.
2) digital camera depreciate. That said the monochromes hold up as well as any others.
3) not sure. But Leica service in the US can be lengthy- some just send back to Germany. I've not had problems.
Overall, the M10M (and the M11M likely but not tried) are exceptional cameras. They are not as good for fine fine images as large film cameras, but they are highly flexible and give very fine results. Not mentioned are the lenses you would need - the Leica ranges vary in expense and how far out on the quality limb you need to go - but CV have been making now some superb lenses. Oddly you can find very good lenses for not much money if you do your homework.
One last note - many people like the older M9M with its CCD sensor, claiming more filmic than the later CMOS sensors. I don't quite see this to be a threshold issue, and would not recommend, as later cameras are much more durable and have much higher ISO capabilities (like shoot in the dark).