It might be worth using a soft white brush to add some extra snow to the path to break it up a little too as the regularity of the path texture is showing through a bit.

In regards to the shadows - they are always a pain. I wish there was some sort of proper/solid shadow plugin or something. But anyway, you would be better of using a much smaller drop shadow with less distance (3-5px), more spread, and a smaller size to tighten it up. This will avoid the floating look but obviously your shadows won't be so pronounced.

The OTHER option which takes a bit more effort is to draw the shadows in manually on a separate layer underneath your buildings using a solid black hard brush (they don't have to be super precise). Then you drop the opacity of the layer right the way down and add some gaussian blur to soften them up.

One final option is to use a big drop shadow but paint the missing corner gaps in manually.