Gotta have this. Definitely a no brainer.
Having the codex and two boxes of core troops is obligatory. You won’t get far without them. Just be warned though: warriors are elite infantry in terms of price and ability. Elite infantry, no matter how good they look on paper, are paper tigers. 7th Edition, and 6th before it, do not look favorably upon the elite infantry. Marauders are cheap and effective. I’m not saying don’t take warriors, just try not to overload on them(as cool as the models are).
Warhammer has some of the best fluff for any game ever. Great choice!
Gotta have it.
The Mega Citadel Paint Set is, while cool and all, just too much. No painter is ever going to need THAT diverse of a pallette. I’d suggest getting some core colors, maybe a few random ones, and then maybe even doubling up on things like chaos black, chainmail, blood red, etc.
Everybody needs a wicked rad lord. Archaeon is, by definition, wicked rad. Whether or not you use him as your own hero or as the actual special character is up to you. A lot of more veteran gamers tend not to use special characters. As cool as they are (even I used them once) they tend to be looked down upon, and seen as more of a ‘newbie’ thing. This is because they are usually very effective, though the special characters often have really cool backgrounds so it’s a shame they get such a bad rap.
Gotta have a hero-choice. See above for special character/normie discussion.
Beasts of Chaos are generally considered to be a little behind the power curve. I’ve only seen them hit the table a few times, but they seem to be pretty effective. They definitely give shooty armies a bit of trouble because of all their skirmishers. To be honest though, I don’t know how the ‘mix and match’ goes between the Hordes and Beasts books, I’ll have to look around.
For tools, you’ll want a decent pair of clippers, some plastic and metal glue, some exacto knives, a decent set of brushes, and a nice place to paint. Gotta find that zen when you work. Take it from me, it’s FAR easier to shell out the money and buy the boxed set than paint the 20 some odd buggers that are in it.