1) "The spin is caused primarily by the position of the controls" - True,
but spins can also be cause by external factors.
2) "...Stick in the aft stop is the 'Stall' position" - Not exactly true. It
is true only with the wings level.
It is possible to fly regularly in a thermal with the stick against the full
aft position, as long as there is some angle of bank (15-20 degrees,
depending on the aircraft).
With the wings level, it will always produce a stall, that's what it is
designed to do.
Any competent flight instructor can demonstrate this if you're too affraid
to try it yourself.

3) "Always fly flatter close to the ground" - Now here is one that REALLY
bothers me.
This is probably the WORST misconception that insists in lingering around
hangar talk, internet talk and in other media with many "experts".
It should be replaced with "Always fly coordinated !" or "Fly with the right
amount of bank for the turn you want to make".
That's the simple, naked, honest truth.

Instilling fear of banking close to the ground is one of the worst things
you can do to your students.
I really hate people who insist on this one.
Gliders will not Stall or Spin due to bank angles. They will do so because
of angle of attack (pitch) not angle of bank.
Since most of us don't have an AOA indicator in our gliders, we use Speed as
an easy way to determine it.

Therefore, if you're maintaining the correct Speed in the traffic pattern,
you can (and SHOULD) bank the glider as appropriate for the turn. ALWAYS.
There is no exception.

A glider will not Stall/Spin from a coordinated turn with the proper speed.

It will do so always from an uncoordinated turn, usually with the Wings
close to level in a skidding turn and the stick aft.
Remember what I said about Wings level and the stick full aft.


Tom Knauff has some excellent material on the subject, published in many
different places, internet, SOARING Magazine, articles, etc.