The Olympics and Paralympics are completely different events, run by separate governing bodies, so they will both have their own Opening and Closing ceremonies. I think it's only in recent years that they've even been hosted at the same time by the same country, as obviously it makes sense for the Paralympics to use the infrastructure that's already in place for the Olympics AND to benefit from the public interest which has already been fired up by the Olympics... I don't think that would work so well if the Paralympics were first.
As for the TV coverage, both events would have been bid for separately by TV companies and it just happens that Chanel 4 won the rights for the Paralympics... I think they got them for Beijing as well... Probably there won't be so many chanels available but, again, it's handled as a completely different contract.