Will I have to declare that I have an account on Form 1040, Schedule B line 7a?
Yes. You will need to answer "yes" to the foreign bank question in the interview section.
What will bank do with the W-9?
The form is pretty simple. You put your name, SSN
and
address and confirm that you're a US tax person, and give it to the bank.
The bank will be heavily penalized if you don't comply with their request, so it is likely that if you refuse to provide them the W9 (and authorization to provide the required information to the IRS) they will refuse to
service
you.
f the account is less than $10,000, I should not have to submit any other document?
You only have to report foreign accounts that exceed the threshold for reporting. The FBAR reporting threshold is if the aggregate value of all foreign financial accounts exceeds $10,000 at any time during the calendar year reported, you must file Form 8938.
https://www.irs.gov/Businesses/Small-Businesses-&-Self-Employed/Report-of-Foreign-Bank-and-Financial...
