Best classes setup?

[Yo-Yo Freak]

you can do that or you can unbind the movement keys from the slave account

[elsegundo]

or you can use a whitelist. so only the keys you designate will get passed.

hunter and shaman are good depending on spec. =]
and make macros to have your slave assist your main somehow. use the wiki up top. it helps.

[Littleburst]

Pretty much any setup can work, everyone has it's ups and downs.

Shaman / hunter or priest / hunter don't make a real big difference i think. Both are good/simple options, since you got a hunter to do the damage and a hybrid to back him up.

Tips: You want to unbind the movement keys on the slave or don't broadcast them to the slave(blacklist). Put the slave on /follow.
I would use the hunter as main, if you use it mainly for dps and the priest for backup it requires more attention then the priest. (FD, if a mob comes into melee range, pet)

/tar hunter / pet
/cast heal
So you can keep shooting with your hunter while getting a heal.

Unbind the arrowkeys on your mainchar, keep them bound on your slave, so you can rotate the slave while still having the mainchar as mainscreen.