Is this sort of thing any good for turning, or shall I just burn it?
"excellent for turning" apparentlyshrinks and moves a lot while drying
That looks fantastic
Don't burn it!
Definately good for turning
is it a good idea to paint the ends to stop cracking?
Yes good idea to seal the ends with thick paint or dissolved paraffin wax. Apple is hard so lends itself to mallet heads, cogs etc.