FMC emergency procedures

Good day folks,It's my premiere in this very forum, although I have been lurking here for the last 3 years!It has always been undoubtly the best source of know-how for this immaculate and realistic piece of art.1. Down to earth - I was wondering about FMC procedures to be used in case of emergency, like engine out for instance. What I mean is, what are the inputs to be done to re-route ourselves to the port of departure. I tried dep/arr page, selecting port of departure landing runway, but FMC draws the line to it from the last waypoint en-route, which is port of arrival. I also tried to select 'descend now' command but apparently with no effect - craft just continues at VNAV altitude. I might be dumb, but cannot figure it out.Say, we fly en-route from A to B and soon after leaving A we need to come back to A. How should I do it?2. A bit OT, but use it with PIC. I set up my CH Yoke with FSUIPC to have the bottom 10% throttle range mapped for reversers. Since I am not ultimately happy with this I attempted to re-map it with full throttle range, thus eliminating reverser part. I pressed reset to get back to original values, then displacing throttle lever tried to set it up again, but it looks like it remembers previous setting, as the forward throttle range starts at some 10% up from the bottom stop. When displacing a lever from the bottom stop up the values do not change until it gets to this 10% length and then increases as it should.I would appreciate your help on that.ThanksJohn