They are not numeric. A container is a variable. It holds a value which can be changed. A container also has a type permanently attached to it that constrains what values it may contain. A variable will sometimes contain no value.
Containers compare by identity only.
Containers are the only things that can change in Avail, greatly simplifying the construction of many design patterns. A tuple is just like the mathematical notion of a tuple - immutable and heterogenous. Provisions exist for describing tuple types that are semi-heterogenous and unbounded. This type is special in that it does not inherit from all. It does inherit from void, though.