More than likely, for these characters there will be an introductory starting area similar to that of the death knight where they can experience the lore of the game in Draenor which brings them up to speed with the lore. Also Blizzard has added the proving grounds in 5.4 which allows players to learn how to tank, heal and DPS, this eases the learning curve and allows you to settle into the game as efficiently and easily as possible. So new players know what they are doing and how to do it, although we will probably be seeing a lot more people asking for help and what to do in /1 (or probably /say) in the starting area in Draenor.Take a look at the site here:WoW Powerleveling.
Rumour : Blizzard Selling Level 90’s
Because people will want level instant 90’s and do similar to what they are doing now and buying SOR accounts online, an action blizzard is desperate to stop as it is promoting the theft of accounts and fraudulent payments. Blizzard may be offering an official service where they will sell boosts for level 90 characters.
Blizzard may be offering this service as it cuts out these suppliers of accounts who have probably stolen these accounts and also stops players from buying more accounts and transferring them over to their new account. There is currently no price set for how much it will cost to buy an instantly boosted 90 character as it is unconfirmed.