As far as I know, titles are considered too short to be copyrighted, so there are no restrictions. But authors will have to be aware of the connotations of any famous title they might wish to use.
Absolutley none. The recent biog of George Carman QC is No Ordinary Man. There is also a forthcoming biography of Cervantes with the same name. The latter was announced before the former, but the lawyer's book came out first and it was too late for the publisher to change the title of the latter. Still, GC QC isn't taking anyone to court over it...