1. Articulation is limited by the diameter of the swaybar, which makes the vehicle a blast to drive fast on the dirt roads. A smaller diameter bar would provide more articulation, but would reduce stability at speed.
It is not a big wheel lifter, as the suspension numbers are better than 95% of the vehicles available.
What is more important than pure articulation numbers is balance. The front has 8", which is better than most IFS trucks and the rear has 10" with the swaybar attached. That makes for a very balanced suspension and allows the 4Runner to perform fantastic. Suspension performance is a highly complex endeavor, and is influenced by spring rate, travel, damping, etc.
Even though my Trooper was considerably more travel, it is no where near as balanced and tactile.
2. Not an issue. Never hit the tank, even on several 3+ rated obstacles. The front factory skidplate could be thicker, but all Toyotas suffer the same.
3. Put 32" tall tires on the 100 and it would make a great comparison. Otherwise, it will be turtle and the hare. 4Runner will outperform the 100 on the fast stuff and tight trails, while your 100 will fair better in the bigger rocks due to tire size. Or I could swap over the 255/85's from the Taco and really play on the rocks