Answering myself partially,
I found a reply by David in another thread that <On Swipe Left|Right> events are planned for release 2.1.9, cf. http://www.tersus.com/#Id=6208.
So I'll go for Next/Previous buttons in the header in the meantime.
Some pointers/advice on working with (collections of) images still welcome, though ;-)
For best results, use the Firefox browser..