Using the Weedon handy-dandy color rule will get you right the vast majority of the time: Green is the only color that can be trumped.
St. Andrew falls on Advent I - which should I observe?
Advent I. You can add the collect for St. Andrew's Day after the appointed collect for Advent I if you wish. Red does not trump violet/blue.
Holy Innocents, Martyrs falls on First Sunday after Christmas - which should I observe? First Sunday after Christmas, again praying the Holy Innocents collect as a second collect if you wish. Red certainly does not trump white.
The Confession of St. Peter falls on Epiphany 2 this year - which should I observe? Here there may be disagreements, but I would argue that you MAY observe Confession of Peter on that Sunday, and likewise the Conversion of St. Paul on the following; however, if you are one of those "Epiphany is ALL WHITE" then no dice. Stick to the Sundays!
That's my counsel on the upcoming months.