ADDENDUM...
Players seeking help with quests or runs to either gain certain items or help gain more XP to level up can ask anyone in the guild who is on. The help received might sometimes seem over-powered, however, this is not to be confused with "power levelling" your 'toon.
Here's an example:
Aiecarumba, a level 32 Draenei Hunter is looking to get help completing a quest chain. Asking over the guild chat channel, the only person free to offer services is Foddermike, a level 70 Dwarven Priest. Foddermike agrees to help, and Aiecarumba has now completed the quest chain.
In the above situation, the only person available to give some help is Foddermike. Now, Fodder only has a level 22 Hunter as his next highest alt, which is clearly no help at all to Aiecarumba, so he goes as his level 70 Priest. For this situation Fodder would tag along, sniffing daisies and inspecting the craftsmanship of various nearby structures for quality or faults, but keeping an eye out so that Aiecarumba doesn't die while attempting to complete the chain quest. Aiecarumba, during all this, is expected to take the lead, fight the mobs and generally operate as though alone, except where situations necessitate a stronger helping hand.
Hopefully this helps better illustrate how helping out others is handled within the guild.
Sincerely,