Depends on the FDC but generally No.  The drive at the end after the twist 
should be set as Drive 0
Since you're using the 5.25 as drive A: it should be at the end after the 
twist with the resistor pack fitted.
Yes

Hope this helps.  I had exactly the same problems.  Unfortunately when
I changed to different machine the problems started again because
of a different FDC.  Seems (don't flame me, this is mainly guess work
from practicle experience) that some FDC's do different things with the 
select.