OK - I found the answer to '1' now - Interpolate is hidden in a 'right click' menu that appears in piano roll view sometimes (but not always).....
I've watched a video (for x1) all about the new 'skylight' interface, but I'm still not sure I 'get it'. I can sort of understand the logic behind contextual menus to shorten long menus to make things easier to find, but if you don't know where to look for something, it can be hard to find it!
Anyway, 1 solved - any thoughts on the others???
Thanks
Paul