I don't think the demand makes it worth exporting them. There used to be a lot of Yamaha organs sold in the US, but the demand dropped off once keyboards and digitals came on the scene. For anyone wanting to buy a new organ in the US these days, your choices are Hammonds, the Hammond clones, Lowrey, Rodgers, Allen, and probably a few more brands I am not thinking of.
Yes, all instruments' sounds were played in real time. Its player can play up to 32 instruments' sounds at the same time (16 instruments for the upper manual, 8 for the lower manual and pedal board separately) by different ways: initial touch, after touch and horizontal touch. There are 16 register buttons between the upper and lower manuals. The maximum number of the registers for a song can be 16x4=64. This song totally uses 31 registers. Registers can be changed by the player's fingers to press these buttons, the right foot to push the register switch or by the instrument automatically. Unlike workstations (synth), arrangers or digital pianos, its sequencer function is very weak. Almost every sound must be played by the performcer except the rhythms. I guess this is one of the reasons why it isn't popular
It needs very long time to arrange a score to a Yamaha organ music (about 4-5 monthes including typing sheet music). Except arranging a song by youself, there are some different ways to play songs on an electon:
1. Using Yamaha preset styles and rhythms. This likes an arranger, such as Tyros but play two manuals and its pedboard. The sheet music for this situation can be only with melodys and chord signs. So, it can be 1, 2 or 3 staffs
2. Yamaha publishes some music books which use those preset a rhythms and styles and tell a player where to use what kind of voice (instrument). The player can set and save them into USB drive. You can edit the voices if it is needed
3. Yamaha sells some puplar songs data and books. Most of them are Japanese songs. A few of them are famous movies' music, such as Star War, Pirates of the Caribbean, etc. But the website, instruction, etc. are in Japanese (I don't understand Japanese). Please refer videos