Few questions about the WOA

Just finished the book and mostly loved it but I have 2 small doubts

1. Why were there cans of food near thee well of ascension? Vin says they were prepared there but it was never explained why 2. Why does Marsh try to kill Sazed? Has he switched sides? That makes no sense cuz at the end of the last book he killed all the other inquisitors at the palace.