A Technique that says it require martial training means, yes the character must be trained in that Technique from a style that has technique listed or the Quality that gives a character access to one technique (See R&G page 128 for costs and relevant pool limits, the quality is on page 127). If you read the full disruption of a technique it will tell you what it effects, keeping in mind penalty decreases are common among techniques.
Some of these are little confusing in 5th, grab and throw being a fairly good example, be very sure you understand the action type of a technique, and how it effects combat, if it's consider an attack, or how it effects action economy.
In general called shots questions are up to your gm for resolution, as a GM i'd allow such a called shot in sub-dual but your millage may very by GM, if it comes up be sure to discuss it with the GM before attempting it. Another thing to keep in mind in a society where DNI is very common even if you disable a targets larynx, there is certainly still a pretty good chance they can still communicate electronically.
In general rendering a target unconscious with stun damage is an easier way to handle silencing a target. Still not perfect by any means but generally safer.