First off, welcome to the club. ;-)

Second, that 25% that they talk about? That's just the long-term average. Theoretically. Depending on how good the PRNG is. In reality, some days it's like 5%, other days it's like 50%. You just have more votes to notice it with at saint than you did at previous levels. For example, when you had 5 votes per day, you could get 1 or 2 XP for using them. Or maybe 3 or 4 - and you probably just thought, "cool!". But when you get 15 or 20 XP for your 40 votes as a saint, you start thinking there's a bias in the system somehow. There isn't, and you'll feel frustrated another day that you manage 2 XP for all 40 votes. I seem to recall a comment about 0 XP for 40 votes one day by holli in the CB at some point a month or two ago, so I know I'm not the only one to suffer from lows. It's kinda like flipping coins - just because the previous 10 flips came up all heads or all tails doesn't influence the next flip.

Of course, when you're posting at the same time as voting, you have to remember that chance that while you were reading a thread, someone upvoted you, and so that XP you just gained was really for your post, not your vote.

AFAIK, they don't.

Here's some documentation of the rules: Level 26: Saint, Voting/Experience System. It says you have "25% chance of gaining 1 XP every time you vote on a node".

There is no difference between saints or any other PerlMonks registered member when it comes to how XP are awarded. Votes cast have the same liklihood of resulting in an XP gain, node reputation has the same effect, and being logged in in the past 24 hours has the same probability of awarding XP in the same quantity.

Actually, I take that back; there is one difference. Lower-level monks do get a little XP perk for using all their votes in a given day. Higher-level monks don't get that.