Answer 1

Given:
1 2 3
4 5 6
7 8 9

Reverse order could mean 9 to 1, but others are possible. Assuming this:

For row from 2 down to 0, ...
For column from 2 down to 0, ...
Print matrix[row, column]
Endfor
Print new line to break it up if wanted
Endfor

Answer 2

test should be i or j >= 0. Values you want are 2, 1, and 0. You got bounds error because -1 is still less than 3.