CFAI Reading 22 - Fixed Inc Part 2 problems

[AlmostDoneIII]

I’m really confused about #27 and #28. Maybe i’m reading to much into it or my understanding is incomplete.
#27) Why is interest rate risk something Choo would be concerned about? I assumed under standard immunization and the use of a callable bond he was duration matched.
#28) I got real thrown off when he wanted to do cash flow matching and didn’t want to use immunization. But when there is just 1 lump sum payment in 5 years and you use a 5-year zero-coupon bond the same thing is immunization?
Someone please clarify, i’m sure it’s something to do with how i’m looking at this.

 

[Glue85]

For 27, even if you have immunized your portfolio, interest rate risk will be immunized for only one time parallel change.
For 28, buying zero coupon bond, when you want to immunize a liability you need to buy a bond that will return the value of the liability at maturity right? If you buy a bond with coupons to immunize your liability , then you will be exposed to reinvestment risk that eventually might make the value of your investment at maturity fall short the liability. On the other hand, if you buy a zero coupon bond, your return of the bond which is the discount value to par is locked already and will not change.