Rules explanation

Hello,
I would like to get some further explanation about this few rules.
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"Other smaller Exploits such as:
- Powerleveling (to bring a low level char to a high level zone to rush its leveling)."
What is considered a high level zone? And how many levels we can "skip" with this system? Ex: Am I allowed to go to Tanaris with my guild mate who is level 80 while Im only level 20? Or I can go even to some 50-58 zone?
Also are we allowed to call a friend into a higher level dungeon so he can practicly solo it for us?
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"NO PVP EXPLOITING

Arena Boosting: It is not allowed. neither paid or for free"
Also for this. I am not allowed to enter arenas with some friend that is very well geared for PvP and practicly be carried by him?
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I know that this question can be answered by players if I posted it Q/A section, but I thought about it and the only answer thats official is from the Staff team.
Thank you for your time.
Icecrown player.