1. Move the list of Paid-only layouts from FAQ 170 to FAQ 145 or more prominently link to FAQ 171.
2. Add information on customized comment pages. As far as I can tell, this information isn't available anywhere in the FAQs yet.
In the end, this would look something like this (edits and counter-suggestions welcome, of course):
I am using S2. Why are some customization options not available?
Some options under S2 are reserved for Paid, Permanent, and Early Adopter accounts.
Some S2 layouts are not available to Free users. Also, even if a layout is available and it supports a customization option, this option may also be reserved. For a list of which layouts and customization options are available, see this FAQ: http://www.livejournal.com/support/faqbrowse.bml?faqid=171.
Customized comment pages are only available to users with Paid or Permanent accounts. All other account types must upgrade to a Paid account in order to use this feature.
Information on how to upgrade to a Paid account to gain access to the reserved features of S2 is available in this FAQ: http://www.livejournal.com/support/faqbrowse.bml?faqid=131. For information on the other benefits of a Paid account, see this FAQ: http://www.livejournal.com/support/faqbrowse.bml?faqid=131.
The last sentence of the FAQ, "For information on switching between style systems, please see http://www.livejournal.com/support/faqbrowse.bml?faqid=168", seems unnecessary to me.