[plt-scheme] PLT vs. the world

Hi,

I'm brand new to Scheme. Can you please tell me what the PLT story is?
My impression so far is that PLT consists of a group of motivated
individuals who want to use Scheme as a productive general purpose
language, and so a number of features have been added to facilitate
that.

It seems to me that a large portion of the Scheme community thinks
that's great, and another large portion is apalled at the rash and
gratuitous extensions to the basic Scheme language. :) When the
subject came up on Reddit, one commenter suggested that PLTers are
very strong marketers of their approach. Others suggested that R6RS
was basically a product of PLT.

Are the changes/additions that PLT makes fluid and subject to
improvement later on? Or are they cast in stone, locked into
backward-compatibility requirements?

Does PLT support the SRFI's (which I'm just learning about) or does
PLT go off in its own direction?

Also, is there a PLT-specific faq or community-edited wiki anywhere
where I might find these questions answered? I see that PLT has
substantial docs, but did not find a link to a FAQ or wiki.

Thanks for any info!