There is an entire forum specifically for new multiboxers, I have linked the newbie starting guide from it below. Having said that, I would strongly suggest you begin boxing in retail when you set up your sub for your second account, just to get a feel for it. A great time to get a feel for boxing would be Aug 13-27, which is after we are allowed to select names on realms, so if you want names you'd need your sub set up and give you 2 weeks to try it out and feel how things work and get some knowledge on how you'd want your setup done instead of going in blind.

1) With 2 boxing, you can do it all manually if you want - drive from the warrior and then just heal from the other class as needed on your other monitor. Using a program will make it a ton easier, if you are serious about multiboxing I will always suggest ISBoxer.
2) For classic, EMA, ISBoxer if using the program, others are optional.
3) I would suggest having your WoW accounts under 1 B.NET account. For classic I don't think there will be a difference, but for retail your "account wide" information is B.NET account wide, so heirlooms, achievements, etc count for both.
4) That would be considered automation. In Vanilla WoW addons existed that would heal the lowest HP target, but it has been stated those won't be allowed in Classic.You will use macros, addons, and/or broadcasting programs that will allow you to heal, attack, and loot on your slaves.


https://www.dual-boxing.com/threads/...to-Multiboxing