The prize structure is never published in advance because it can't be - they need to know how many entrants there are to work it out, and they don't know that until the end of buy-ins on Day 1D. What's been said above is correct, they generally pay about 10% of the field. The way they chop that prize money up (ie: how top or bottom heavy the payouts are) changes from year to year though.
Disclaimer: the rest of this post is informed by what I've read on blogs and whatnot, I've got no first-hand experience with any of it.
Players who get seated at a TV table are usually offered somewhere in the vicinity of $10K (for the Main Event) to wear a patch. Which is why the players at Phil Ivey's Day 1 table were a bit pissy this year when he used his influence to make sure his table wasn't on TV - they would've all been on a freeroll if the table had've been televised. Rumour was he paid them something himself in compensation.
Signed pros (as opposed to everyday schmoes who just happen to land a seat at a TV table - we're talking the Iveys, Negreanus and Hellmuths of the world) probably get their entries paid depending on their deal. Some will be contingent on whether the tournament is being televised, which is why the field in the $50K HORSE was down this year.
And if you win a satellite on an online site, I'm pretty sure I've read the buy-in money is yours to do what you like with (ie: you don't actually have to enter the tournament) but if you play and agree to wear a patch the site might pay your accommodation or something. That might not happen anymore though, IDK.
