It I see mostly the case but not always the case. You need to check when the past service cost arose as to whether it needs interest unwound upon it. If it arose a thing the start of the year then it will, if it arose at the end of the year then it won’t.
Yes, the interest rate used is the same for both assets and liabilities. Under old rules it didn’t have to and different rates were used, but this now no longer applies.