The team question is easy, if you're part of a team, and your team wins, you'll get credit for the win no matter what, even if you got eliminated or booted. That said, your boot rate will still go up, so it's not really recommended.
The luck question is not so easy.
What you're thinking of there is what's known as kill rates, The typical WarLight game has it set at 60% attacking kill rate and 70% defending kill rate. That means that in a single attack of 100 vs 100, you could expect 70 attacking armies to die, and 60 defending armies to die, leaving it at 30 vs 40.
Now that's on average. When a luck factor is included, a random roll of the dice determines a different number of armies killed for both sides, by looking at each individual army and giving them a 60 or 70 percent chance of death.
Now, once WarLight has calculated the random number of armies killed and the average number of armies killed, it takes a weighted average of the numbers, based on the luck value. At 100% luck, it will completely ignore the average number, while at 0% luck, it completely ignores the random number. Anywhere inbetween it calculates using the following formula:
armiesKilled = randomKilled*luck+averageKilled*(1-luck)
where luck is the decimal number, not percent.
Hope that helped!
Edit: Oh, and that info came from the WarLight wiki. You can read more here: http://wiki.warlight.net/index.php/Luck_Modifier
Edited 6/7/2014 02:51:03