What You need know addtional:
All T5240 alway have Two UltraSPARC T2 Plus multicore processors.
CPUs 1.2GHz 4-Core (32 ×2 for a total of 64 concurrent threads)
1.2GHz 6-Core (48 ×2 for a total of 96 concurrent threads)
1.2GHz 8-Core (64 ×2 for a total of 128 concurrent threads)
1.4GHz 8-Core (64 ×2 for a total of 128 concurrent threads)
So answer for question 2,3 is fixed:
System should have two installed CPU. No free socket.