This question comes up because older FCOMs say it is transfer bus 1 and newer ones say it is bus 2.
Based on what you wrote its xfer Bus 2.It needs 115 AC in any case.My manual shows Xfer bus 1.
2- what happens if the ground power is switched on bus while the bus transfer switch is in the Off position? Which buses are energized?
That is purely a theoretical question as the transfer bus must be on the auto position on the ground...
The ground power powers both AC transfer buses,when the transfer switch is in the OFF position,the transfer buses are isolated from one another but still powered by the GPU.