1 - opener is still EB > Flurry+IV > IL > Forb > normal rotation
2 - yes Bracers are BiS but they aren't game breaking. Still havent got my frost Bracers yet and I have 2 legendaries to go. You don't monitor the buff though, treat it as a passive. They will still be BiS generally especially if you can run 2+4pce.
3. Never cancel casts. Just munch the Icelance.
4. Mastery is utter crap unless you're playing fire, so save off-spec gear if you plan to play fire ever. You pretty much dance around shatter cap and get vers/haste as high as you can. Even for GS I wouldn't say mastery is good to stack so yeah.
5. Im at work so i cant really take a look at logs or gear but
Https://discord.me/alteredtime is the mage discord. And here is the mage website
https://www.altered-time.com/forum/index.php