Yes, the 1065 needs to be marked as final.  As a side note, if an extension was not filed, it is probably late with fairly large penalties.

No, unless the Single Member LLC wants to be taxed as a corporation, 8832 would not be needed.

Because the 1065 is being marked as "final", it is possible that if the Single Member LLC need to use the LLC's EIN (such as for employees), they might need to contact the IRS EIN office to let them know about the situation.  But if there are no employees, excise taxes, or employer retirement plans that need the EIN of the LLC, you may just leave it or cancel the EIN.