I had a long post ready, and I thought even submitted, but I lost it somehow.. ah well.
I am going to have to start by disagreeing about Shadowrun being the deadliest RPG ever. I don't think I've ever had a starting Shadowrun PC die because a rat bit him, and did more than his 1hp of damage. That, and Shadowrun has the Hand of God feature, that makes it very hard, actually, to kill a PC that the player doesn't want to let die. When I want deadly, I usually go with Cyberpunk 2020 over Shadowrun, but that's just me.
But anyway. Many of my players get very attached to their characters, and I actually like it when players are attached to their PCs. It makes them think better. When you aren't attached to your PC, it's real easy to do dick things that are likely not only to screw your own PC, but the group as well. When players are attached to their PCs, they flesh them out more, give you interesting backstories, adventure hooks, and world building even.
As for handling character death. I think I've only really had 1 PC die in games that I have run. I've had my own PCs die in games, but usually in temporary death games, where something in the world existed to either prevent outright death, or to bring back from the dead. So, this one is a hard one to answer
As for long term games. My current shadowrun started not too long before the physical book of SR5 came out, and we're still playing it. We go every other week, and I have been putting them through 1st edition stuff. They've done Silver Angel, Mercurial, part of Harlequin, I've had longer running games in other systems, and the length of a campaign, in my opinion, depends heavily on just how attached players are to their PCs.. if they are too detached, then the game probably won't last very long.