We sold and implement quite a number of P4000 Hardware and Lefthand VSA (Virtual SAN Appliance) for vSphere4 projects.
1) Yes it makes your local HDD to be an iSCSI SAN that can be shared by other ESXi hosts
2) Yes, even if the other hardware does not have Lefthand VSA or sufficient HDD space, you can have it mount via iSCSI to the initial host that Lefthand VSA is running
3) As long as its gigabit with latency of less than 5ms, you're good to go ..
iDLE-jAM | VCP 2, VCP 3 & VCP 4
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