To merge two files? Not directly possible. But you can of course group elements, save that as vob and load that into another scene again. Regarding display quality. You can change that for whole Vue in the preferences. Surprisingly under display options. You have two sliders that you should try out. But keep in mind how the original setting was - there is not really a reset! Try to switch of background drawing - this makes display slower and is not really necessary probably. No downloadable manual for the demo version, no. Only one for registered users.

One day your ship comes in - but you're at the airport.