If TW's reality show can come in and make them more money (which, with a lower overhead would be practically guaranteed )then Smallville may be a goner.
I suspect that TW's reality show is part of a not so sneaky quid pro quo deal struck when he signed on for another two seasons. It's there to keep the cost of SV in check by spreading TW's overall compensation around a bit.
1) Do the networks sell ad time at a set price for the entire year, or can the price vary based on ratings? I saw that TVD, for instance, had a relatively low commercial price, relative to its ratings (total and W 18-34). I know that if ratings drop below a certain level, the network has to give sponsors "make-up" time to cover their loss. Does that make the reverse also true?
It's my understanding they sell as much as possible up front. They would have to keep a certain amount of commercial time in reserve so to speak in case as you mentioned lower than expected ratings require "make-up" time. OTOH if ratings are higher than expected the reserved time could be sold at a higher rate on an ad-hoc basis.
2) If a show is cancelled, what is the network required to do for commerical time already sold for that time slot? Does the altrnative programming need to stay at the levels agreed upon for the cancelled show? Shifting repeats of TVD rather than MP to fill the hole on Wednesdays makes me think this may be the case, but I could certainly be wrong.
Don't know that one. But I think you're right.
3) How do November and February sweeps period influence ad rates?
I think they're primarily for affiliates trying to sell local/regional ads since the majority of national ads are committed up front. Though I'm sure they're often used as leverage when rates for national ads purchased after the up fronts are negotiated.
4) If networks sell ad time based on each specific show, why do they change their programing schedule during sweeps? Fox is notorious for showing lots of House repeats during sweeps, and they have basically anounced they plan to do it again this year on Fridays.
Like with #3 I think the sweeps are mostly for affiliates where advertising isn't so much tied to a certain show as it is tied to a certain station and that's why they are able to get away with switching their programming around. Not only would I expect that local advertisers aren't as savvy as the the national ones they likely have a lot less leverage when it comes to negotiating rates.