Are all abilities affecting your stuff blocked or only those affecting the player?
Only the player. I toyed with the idea of it protecting your weapon and shield too, but decided that was unnecessary complexity. The card specifically says "you", though I guess that could be more clear.
For example, are devour or BE stopped?
They are not.
Also, does the effect deal with 'on attack only' stuff or are things like chrissoara blocked too?
Chrysoara is stopped too as it affects the player.
Do Titan and Discord work, as long as they are not flown?
If not flown they work, if flown they don't.
Is catapult blocked? Is the bonus a flying Farenheit gets blocked?
Catapult is not as it's a permanent doing the damage. Flown Fahrenheit is since it's a creature at the time.