Also - how do we get polyphony. It seems only monophonic is working. Oy.

The effects like trumpet plunger, doits, fall-offs are not available through keyswitching. They are assigned to midi controls which you can enter in the CC piano roll while editing. You could theoretically assign these midi CC's to knobs or sliders on your midi controller, but you would need 4 hands to play the notes in and ride the mod wheel and other CC controls at the same time. It's much easier to add after you've played the part in while in piano roll.

Regarding polyphony, I might be wrong since I haven't used JABB recently, but I think the instruments are monophonic. The idea was to build a jazz ensemble using separate instruments. That said, I vaguely remember there being a work-around to allow for polyphonic playing, don't know what it is though.

To get polyphonic instruments in JABB use the 'lite' instruments.  The lite variants are polyphonic as long as auto-legato is NOT enabled (See the ARIA control panel for an active instrument, also note that CC113, 127 can remotely toggle it on, while CC113,0 toggles it off).

Note, that anytime auto-legato is enabled, it's impossible for the instrument to be polyphonic.  Auto legato mode causes notes that are 'overlapped' to be 'slurred' and possibly adds some amount of automatic portamento.  If auto legato is NOT enabled, most (with some exceptions) Garritan instruments will then work in polyphony.  When auto-legato is NOT enabled, CC68 (or CC64 from some wind and string instruments) can engage legato.

The full blown variants of wind instruments in JABB really need a monophonic stave (or voice/channel) of their own because of the advanced CC based sound shaping abilities inherent in those 'solo' instruments.  They were designed to be more expressive 'solo instruments'....after-touch, portamento, slurs, shakes, doits, filter manipulation, etc...they just wouldn't work well with divisi writing on a single stave/channel.  It doesn't make sense for the same trumpet player to be making chords or playing more than one part at once....these were meant to give you 5 unique and individual jazz trumpters, each playing one note at the time (each one is a sample set of the same instrument/player).

If you want parts to print in a more condensed style (divisi on a single stave), then keep your 'play-back tracks' separate (one for each virtual player in your ensemble) and hide them from view (they will show in scroll mode, but be hidden in page mode).  Mute your 'visual' divisi staves so the sound only comes from your hidden 'play-back' staves.