How is interest paid out on these brokered cd’s? can it be sent to a separate vanguard / external account if you don’t want to roll it back into the CD ?
Answers

from Vanguard:
"When does a brokered CD pay interest?
"The issuing bank determines when it will pay interest on the brokered CD. Generally, interest is paid at maturities of one year or less. Sometimes banks pay interest monthly. For maturities beyond one year, banks may pay interest semiannually, quarterly, or monthly. To see the payment schedule, select the issuing bank and review the description."
https://investor.vanguard.com/investment-products/cds
The interest will be paid into your Vanguard settlement fund. That will happen regardless of what you may or may not "want".
See https://personal.vanguard.com/us/content/Funds/FundsCertOfDepositOVContent.jsp