Yeah the only reason you don't like your main account is so that you can use a character to boost 4 alts at once through instances. Leveling with 5 chracters 1-60 is pretty quick these days, especially with RAF, so it's your call on what you think is easier. Boosting is definitly faster, but not the funnest thing in the world. It took me about 15ish played hours to boost 1-60 RAFd toons with a 70 lock...with an 80 it might be alot faster.

TBH I think a level 80 resto shaman in 3.0.8 would be a crazy good booster, you could probably do strat in 3 pulls keeping yourself alive with heals easily while threatless magma totem kills everything in short order. This is assuming you get exp if magma totem does 100% of the damage to a target...I know for a fact that pets doing 100% damage on a target won't give you exp, but mabey totems are different

You can still link your chain to a friends account sense the free levels/mount from account A just get wasted otherwise (this has nothing to do with playing someone elses account, your just forwarding the RAF benefits to them as your RAF parent)