If you look on Google maps you'll see that Greasley and Newthorpe are actually less than a mile apart, so I wouldn't read too much into the change of PoB, depite the change of county.
Given that there doesn't seem to be a baptism for some of the other children it's possibly that, for some reason they didn't bother having Enoch baptised either.
I too am assuming that both Sarah & George aka Thomas died between the census returns. There's a couple of deaths on Free BMD for Melton Mowbray which would be just across the county border from Willoughby that could feasibly them, it's only about 10 miles away, but you'd need to order the certificates to prove it, or see if someone is able to do a look up for you for on the Melton Mowbray records.
Sarah Ann Stapleford Dec 1/4 1862
Thomas Stapleford Sept 1/4 1866 aged 62
Best Wishes
BG
