Ocala is really nice, and you do have the Disney welcome center there, along with most of the major hotel chains. Still, if it were me, coming from so far as you are I'd probably stop a bit farther north (so the first day's drive is not quite so exhausting). Lake City, Florida is one possibility (I can personally recommend the Hampton Inn there) while still being just a few hours from WDW. Valdosta, Georgia would also be a good choice about an hour further north from Lake City (I've stayed at the Holiday Inn there - right by the interstate - but it's been a few years).
The one thing I can absolutely suggest is making advance reservations somewhere (the morning of arrival is sufficient), for these I-75 locations seem to so often book solid by early evening.