Can I ask any advice on what I can do to change the tempo of a midi drum filll once it's imported into the piano roll.   It seems to have originally been made at speed 100 whereas the rest of the song I'm putting together is 85 bmp. How would I permanently change it to 85?

Why don't you just change the samples pitch, by changing the 'pitch' or by taking it down a few notes in the keyboard editor until it sounds right. you can fine tune it in the 'channel settings' window.
You could also load it into the 'Slicer', that way you could keep the pitch/tone and get the right timing by tightening or widening the slices after you've exported them to the piano role.
Someone else might have other suggestions !!??