Octaves and split clefs

I have two problems with the extract on this attachment.

1. I can add the 8va marking to the chord on the 2nd beat but MuseScore wants to extend it over the rest of the bar. I can drag it back so it only covers the beat which is fine for reading but is not reproduced in playback. How can I make it apply to just the one beat.

2. How can I reproduce the semi-quavers going from the lower to the upper stave in the second bar? It's quite a common feature of piano music so it must be possible!