[benjaminclark]

Th article does cover these.

For #1, see the section headed "The risk of non-payment". Prior to the mortgages going into the pool, insurance against default is purchased from a GSE. In exchange for this insurance payment, in the event of default, the GSE buys back the mortgage for the remaining principle balance. So as an investor in the typical MBS, you don't face this risk.

For #2 and #3, while it could go into it in more detail, this is discussed in the section titled "Every other risk you could imagine, of which there are many". It notes that the value does change as a result of interest rate changes (in the context of noting this as a key reason why most mortgages are not held by banks, but other institutional investors which can better tolerate this interest rate risk).