Snoonyb-
I think your "pre-mixed" is generally referred to as "Ready-mix" in the construction industry.
Ready-mix does not use common cement, but uses any one of the types of Portland cement (Type I, Type II, Type III and Type IV and the most common types). Ready mix is delivered to the site by the supplier and anything added to it within the truck should be noted on the delivery ticket.
There is no such thing as "red label cement", but bagged cement is is available in many different types or colors of bags. Colors have noting to do with "water resistant"properties since they are determined by the mix design, aggregate gradations and placement practices.
The key is common with all segmental retaining wall units (SRWs by specification), but it a part of the SRW units to provided shear resistance. From a structural standpoint a low wall is a gravity wall and the failure is a shear failure. That is the reason all SRWs have a designed lateral resistance in the form of shear keys or pins. - that usually adequate up to the common codes requirements that state that the wall must be engineered is it is over 4' or 5'.
I won't address the reference to ladder reinforcement, but you might be alluding to something like "geogrid" that is used for soil reinforcement by engineers.
Dick