stevey- Can you win this game and always be 100% truthfull with everyone?
Definitely, although the willingness to dip somewhat below 100% may make it easier, depending on how you do it.
The way you win with 100% truthfulness is either to fly under the radar or align yourself with people who make it deep into the game ... or just win all the challenges I suppose.
I don't believe I've lied to anyone in the game. At a couple points I allowed people to form or maintain incorrect beliefs without correcting them, so perhaps that's less than 100% truthful, but I've never outright lied and I don't intend to. Of course, I really didn't communicate with many people up until the last couple challenges, so didn't have all that many opportunities to lie.
Regarding throwing challenges: I suppose it wouldn't be cheating, but it certainly isn't sportsmanlike. So far as I'm aware this hasn't happened, but it certainly could (have).