I am grateful for feedback on my attempts so far, and one thing a couple of people have told me is that the images go by too fast, and up until now I couldn't find a way of changing this. I knew there must be a way, and yesterday I found it. By double-clicking on a frame I accessed video clip and on this I could not only change the length of the still, but also choose an effect. I think such things need to be used in moderation, but the 'vignette' and 'cartoon' effects were useful here for the shamanic journey sequences.
One problem with increasing the length of frame was that the music ran out. However, I have now also made another useful discovery, under 'Window' and 'Audio Adjustment' I can gradually mute one track while introducing another.