It seems to me that you have two separate issues: viewing images larger prior to importing, and something not working right when you delete Images.
The solution to the first is to use a card reader (I don't think this works with the camera cabled to the computer, but go ahead and try it). When a card is in a card reader and you have Aperture's Import window open, you can double-click an Image to see it larger. (The card reader is a drive to the OS. Double-clicking to go to a larger view works on any file on a drive.) There are actually three states for the Import file display window: a browser (grid), a viewer (single image, large), and a list. There are icons for these in the Tool Strip (which is what Aperture calls the large bottom border when it holds buttons).
The second issue is: why when you delete Images from a Project are your Originals not deleted. When you delete the last remaining Image of an Original, the Original should be deleted as well. Are you emptying the Aperture Trash? And then the system trash?
There should be no change in the storage requirements between deleting files prior to importing into Aperture, and importing into Aperture and deleting all the Versions of an Original (which forces the deletion of the Original) and emptying the Aperture Trash. (In both cases you have to empty the system trash to recover the storage space.)
Once you get deleting to work properly, I recommend as a workflow importing all images from every shoot, and then doing your triage in Aperture. It is one of the many things Aperture excels at. What I do is quickly mark as rejected any Image that is OoF, mis-composed, or otherwise not worth saving. These are removed from view as soon as I select another Image (because the default Browser filter is "{Show} Unrated or Better"). Then at some point while the shoot is still fresh in my mind, I filter the Project to show rejected Images, scan through them to make sure there is nothing there I might find useful, and then I select what's left and delete them. At the end of every work day I empty the Aperture Trash, and after closing Aperture empty the system trash (prior to unmounting external drives).
