Lankhmar, Conan, EC Books Question

Mongoose is doing Lankhmar/Nehwon stuff, as well as (evidently) Corum and Hawkmoon and Hyboria. All of which sounds pretty exciting to me! (and will probably persuade me to buy MRQ despite my reservations)

My question is this: will these setting books, when combined with the main rulebook, contain all the rules? Or will you also have to own the Companion and Monster books? And by "all the rules" I don't mean all the rules necessary to run a hamstrung game... I mean all the rules needed to get the full experience of that world.
Certainly the main rulebook contains only the bones, rather than a fully fleshed out system. For example, the list of rune magic spells is quite brief - due to the confines of space. A couple of the runes have only one spell tied in to them. The Companion contains details of sorcery, divine magic, etc.

RQ Monsters contains a mixture of generic creatures and Gloranthan beasts. There's nothing specifically 'Lankhmarian' in there, for example.

I would imagaine that the Lankhmar sourcebook will flesh out specific creatures, magic, etc. for that setting. Hopefully it'll be the same for the other setting books. I can't see how else it'll work.