As to having to verbalize crypsis, it was shown in one of the following strip he was already veiling by then, shown by the dragon not being croaked
-Also, we don't know that to be the only "magic word" for a veil. Perhaps edit it to "caster verbalizes something such as 'Crypsis'"?
The limitation of not being able to Veil troops with the casters linked, IMHO, isn't related to the link itself but to the fact that the foolamancer wouldn't be in the unit and the obvious drawbacks of sending the whole link to battle. I don't think linking the casters would have a limitation like that.