These do not add 100TP, and it is not a total bonus of 166TP. Mavi Tayt +1 add 25TP to Efflux, and the +2 add 50. That brings Efflux to a total of +125TP or +150TP respectively in addition to multiplying base damage.
The "Enhances Efflux Effect" adds a 100 tp bringing efflux to a total boost of +166 tp. The pants need to stay equipped from time of JA use until after spell is cast.
This should be the case anyways as you should have these equipped when casting all blue magic!
These are certainly sexy for physical spells and TPing, however you were off on a few things. Blue Magic Skill increases damage tiers for physical spells, and offers no accuracy. It does however follow the 1 Skill / 1 Magic Accuracy rule for magical Blue magic. No higher haste on legs for Blue Mage, and no higher STR either for Vorpal Blade.
With great stat enhancements of STR and DEX, this piece offers a nice boost to spell modifiers as well as accuracy with Blue Magic Skill. For TPing, few pieces offer more than the 4% haste on a leg piece. Full time? There are higher STR pieces for Vorpal Blade, but if you don't have them, this will suffice for easily 99% of your BLUing.