Answer 1

It's easier to see and forces multiple objects to all be the same type.
Example/
Which is easier to read?
1)
int a, b[], array[], sum, tark[][], c, d[], input, chart[][], f[];
Or
2)
int a, sum, c, input;
int[] b, array, d, f;
int[][] tark, chart;
Notice in the second part you only needed to look at the left side to find out the type.
In the first one you need must look for the name of the object when they're all clumped together.
This is more of an extreme example but hopefully you get the point.