Though u've asked Experts to reply ur query, but i hope u and experts out there wont mind if a novice like me dare to reply 
Basic and primary purpose of both (Waxes & sealants) is same, i.e to provide protection alongwith beauty.
To put it simple i explain each separately:
Waxes
A Carnauba Wax (finishing wax) offers no cleaning ability with the focus on maximizing beauty with the protection based upon naturally occurring ingredients (Carnauba).
Sealants
A Sealant (finishing sealant) offers no cleaning ability with the focus on maximizing beauty with the protection based upon synthetic ingredients (Man-made synthetic polymerization).
Hybrids
There is one more group into which waxes and sealant fall into and that would be the hybrid category. Hybrids contain a combination of both natural and synthetic ingredients.
Waxes are made Hybrid to increase durability/longevity and protection.
Whereas sealants are made hybrid in order to bring that particular carnauba type warmth and look.
Now its user's choice as to how often he waxes his ride depending on the weather/climatic conditions and his Obssession to detail 
As far as layering is concerned, there is no harm in layering sealant over sealant, or wax over sealant; As long as the final layer is a finishing (having no cleaning agents) LSP. By the way, Meguiar's #26 is a Hybrid finishing Wax.
I hope experts agree with me(H)