I saw many games ended at the same time, was there a deadline for the season?
And how was the 'winner' selected?

Yes, each season lasts 60 days. At the end of the season any games that players didn't finish are automatically ended, with the winner being the person who has highest (income * 2 + number of armies).

See http://wiki.warlight.net/index.php/Seasonal_Ladder

Any way such endings could be part of regular games' settings (as turn limits)?

For example, I want to play an FFA on a certain map and know the games can sometimes last 50-100 turns. With turn limits, a winner could be determined in 20, 30 or 40 turns...

http://WarLight.net/MultiPlayer.aspx?GameID=2440032

He won by 1 army!! grr..!!

what would happen if there was a draw? a winner picked at random?

Ouch, mine was a close one too. I might even give myself the advantage with his biggest stack being in Greenland and not of any immediate use.

http://warlight.net/MultiPlayer.aspx?GameID=2453690

Yeah PFC, I'd say that you have that game won. You had much better expansion prospects, and your armies were better placed for fighting. His army in Greenland was many turns away from being useful.

I know that you can easily know when you're running out of time because the date that the season ends is readily available, but is there some way you could give a warning 2-3 days before the end of the season so that people have just a little more notice and can try to finish games quicker?

That seems like a good suggestion Eagle. I forgot (or never read, I don't recall now) about the sudden season end, and was not prepared for it.

Part of the problem is that we are at the mercy of the other people we are playing against. My last game went on for more than a month, due to the other person playing once per 2-3 days. So I finished 19 games in a month, and then played another game the rest of the season, until auto-ended. Luckily I was probably losing, so it wasn't a big deal for me. I still had a chance though, and some people were probably going to win before they got auto-surrendered.