Images are not working with compass helpers

[almozavr]

Scope

Environment with compass and Sinatra::CompassSupport

Problem

Compass image-related helper directives (image-url, image-height) doesn't work without additional compass images-path configuration. But supposed too? Also note, image-height doesn't work, without trailing / at the end of images-path.
Here is the screen with details:

[almozavr]

Also, I found strange cache suffix being after .png, as asset-pack guide says it generates it the same as for .css files... Why?