The SCOPES trial was a big sham..

Well, I don't think Darrow and Bryan (or Judge Raulston) planned anything -- in fact, they were the only three people who actually took the trial seriously. But, yes: everybody else made it into a big media circus, including Scopes. The whole trial was a publicity scam to make more money for the Dayton community. Nobody really cared if Darwin's theories were real or not, sadly. It was just a big capitalistic cash-in.

"What I don't understand is how we're going to stay alive this winter."

You're partly right.

Darrow wanted to challenge the Tennessee anti-evolution law, and he knew that to do so, he had to begin with a local court before it could be appealed to the state Supreme Court. So his legal team needed a volunteer "martyr" and found it in Scopes - who agreed to admit to teaching evolution while a substitute science teacher.

Apart from his initial arrest, he never spent any time in jail and was never reviled by the townspeople of Dayton, most of whom enjoyed the hype that the case generated and didn't care all that much about the issue.

However, William Jennings Bryan was indeed a religious fundamentalist who took up creationism as his last pet populist cause. He may not have been a "young Earth" creationist (it wasn't Darrow's rhetoric that made him confess that a Biblical "day" wasn't necessarily 24 hours, Bryan thought so all along), and he wasn't nearly as ignorant as the film portrays his alter ego (he took the trouble to read Darwin's Origin of Species, for one thing), but he was a true believer in the creationist cause, just as Darrow was a true believer in secularism.