Thanks for your prompt answers to my last question.
One last thing..

Line 5 of the W-8BEN asks for a US ITIN. Does that mean my non-resident, non-citizen needs a US ITIN even if he/she does not have a US physical presence?

Can this line be left blank? The instructions are very confusing!

Thanks again.

Since your sub-contractor is not in the US, he does not need an ITIN. That would only be required to claim a tax treaty exemption.
In order to establish that the subcontractor is not a US person only, he does not need an TIN. Do not fill out part II.