
FY87 Vipers have the extra chaff/flare dispensers, so they don't need the PIDS. Hence you are most likely to find it on FY86 and older Vipers.
The anser to your questions:
1) Always outwards - away from the centerline. You do not want a flare to by any chance ignite the fueltanks, however unlikelly this may seem.
2) Initially, you could not use JDAM's on PIDS as they lacked some software needed. This has however changed, and you can now load anything on a PIDS pylon.
3) ANG usually only carries 1 PIDS and 1 normal pylon at a time. Some NATO forces - Denmark, Norway, The Netherlands - have been seen carrying PIDS on both sides. Norway has 1 PIDS and 1 EPIDS these days.