It gave me an error also, I just opened up yahoo fantasy football in another link, went to join league, copied the league ID from the broken page, entered password, and bam I was in. Just had to work around.
Scoring looks good, the only thing I see with the bonuses is that given the current state of the NFL and how much passing there is, 100 yard rushing games (and higher) will be the rarest of all the bonus levels and might be worth higher compensation?