Contents of a CMO security offering with sequential annual pay tranches

Rules of cash distributions to $A,B$ and $Z$ : interest is paid currently on tranches A and $B,$

but it is not paid on tranche $Z$ until principal on the other tranches is repaid. For tranche $Z,$ interest

will be accured and accumulated into the investment balance. In addition, to ensure that

the maturity of tranche A securities is kept relatively short, the interest accrued to tranche $Z$ and

all current amortization of principal and prepayments from the entire mortgage pool will be allocated

to tranche $A,$ and then to tranche $B.$

Questions

Suppose that there are no prepayment and no default, what are the cash flows for

Class A$,$ Class B and Class Z bonds? What is the IRR for the issuer?

Suppose that there are $10\%$ prepayment and no default, what are the cash flows for

Class A$,$ Class B and Class Z bonds? What is the IRR for the issuer?

Please briefly discuss your findings.