Array Algorithm Question

1.  Given an image represented by NxN matrix. Each pixel is represented by 4 bytes. Write a method to rotate image by 90 degree. Can you do in place ?
2. Write an algo so that if an element in MxN matrix is 0 then entire row and column are set to 0.
3. Given the array of integer. Find contiguous sequence of array with largest sum. Return sum and also calculate the start and end index of sub-array.
4. Design algo to find pair of integer in a given array with specified sum.