On #1: The Farseer will always be an independent character, regardless of whether he has a retinue or not. Are you asking if the Farseer can leave the squad? Doesn't matter anyway, since warlocks are apparently not a retinue.
An Independent Character with a Retinue does not count as being an IC until its Retinue is annihilated...
Here's a couple more:
20) If a skimmer with vectored engines that moved >6" is immobilized by enemy shooting, can it suffer a penetrating hit from subsequent shooting in the same shooting phase.
I'm pretty sure the answer to the above is Yes. The SMF rules on pg. 69 of the BGB specify a "mobile" skimmer. Once the skimmer becomes immobile, it can be penetrated.
21) If a skimmer transport with vectored engines that moved >6" is immobilezed, and it then suffers a destroyed result or penetrating hit during the same game turn, what movement distance is used when determining the emergency disembarkation effect for the transported unit.
Unfortunately, it looks like the skimmer would count as moving >6", as the rules for emergency disembarkation only specify the vehicle's last move. The fact that the vehicle landed prior to being destroyed doesn't seem to save the passengers from damage.