Troubles with isometric grid

This is my first time working with an isometric grid!

The grid is 60x30 with an offset position of 20 pixels on the x axis.

Problem #1: When dragging a structure (snap grid on), instead of it moving along the isometric grid line, it goes straight down, straight across, or straight up. How do I snap the structure to each grid square instead of it skipping over?

Problem #2: When rotating a structure that is the size of 2x1 grid, the structure no longer snaps to the grid and is off center. How do I make sure a structure that is longer than 1 grid tile stays aligned with the grid when rotated?

Thanks in advance!