I'll generally just lock the rear wheel to something, sometimes through the luggage rack - there's no real way to lock the frame, but it hasn't been a problem yet (I suspect it's a less attractive target for thieves than a conventional bike). Moving it around a building is pretty much the same as an upright - it's a little longer but still just about fits in trains, bicycle racks etc., and you can wheel it around upright on its rear wheel the same way as an upright - I do this to get it in the lift at home. At home I just keep it in the hallway of my flat, inside my front door on the third floor (there are bike racks outside but I've had too many bikes stolen from there in the past).

At work I can't actually fit it in the wheel slots of the racks they've got but that's more about having wide tyres/tubes than it being a recumbent (an upright mountain bike would have the same problem) - I've got a stand so I just park it in the rack row resting on its stand, it takes up the same amount of space (no problem with having other bikes in the slots on either side).

I went for the above seat steering - I do touring in various countries so didn't want anything that would be too unconventional / hard to fix.

I found moving it around in buildings (HP Velotechnik Speedmachine) quite a lot more cumbersome than my regular trekking bicycle. Fitting it through doors/elevators (especially with panniers) but I guess that is what you are eluding to, wheeling it upright and all that.

Did you ever bring it on a train in the UK?

Obviously it's a little longer than an upright (possibly helps that I'm fairly short), so the threshold for how tight a corner is before I have to put it vertical is a little lower than it would be for an upright. But I was mostly thinking of cases where you'd have to do the same either way - my building's lift is too small to fit any kind of bike without putting it vertical on its rear wheel.

And yeah I take it on UK trains fairly often.