Dogil, you can put EPS vectors in image frames so you can "crop" them but - I think - they will still be embedded in the SLA. Also, the bitmap preview that Scribus uses to display EPSes isn't very good quality (export should be fine though). And, Scribus doesn't handle all EPS features - as it doesn't handle all SVG features - so what you get might not be what you started with.
LilZebra, Scribus doesn't import SVGs into a frame. The vectors are handled like any other drawn item such as shapes, polygons, etc. They are grouped when you import them so they look like a frame but it's just a group and not a frame.