A) George Lucas owns the copyright to the Star Wars franchise.
B) George Lucas is the CEO of Lucasfilm Ltd. LFL owns the rights to the cuts of the films that were released between 1977-1983.
C) If, for instance, Universal or whoever owned the rights to those films, then Lucas (as copyright holder) would still be able to have his SE's because said SE's would be a new product and not the original '77-'83 cuts.
D) To Clarify, the Special Editions are recognized under US law (17 U.S.C. section 101) as a "Derivative Work," and completely separate from the '77-'83 cuts.
Since this is a SW/Beatles thread, a suitable comparison would be when Paul McCartney released "Give My Regards to Broad Street" album in 1984. The album had several re-workings of Beatles songs like 'For No One,' among others. Macca did not have to pay EMI/Capitol anything to release those songs as they were not the original recordings made by the Beatles in the 1960's. He might have had to pay Michael Jackson or whoever had the controlling share of Northern Songs Ltd. at the time, but he didn't have to pay EMI/Capitol a dime.
That being said, I would refer your forthcoming questions to Section 106 of the Copyright Act of 1976.