Basic questions

I'm trying to get a handle on Aperture vs iPhoto11. I've imported photos from folders into Aperture, deleted the folders, and Aperture can't then find the referenced files now, so I've had to restore all the deleted folders.

Should I be importing every photo into iPhoto11 and then only importing the photos I want to do more work with to Aperture? Ie keeping most of my library in iPhoto11 apart from a few recent imports.

I'm trying to avoid a huge amount of duplication as well as keeping things organised.

I also don't know how to now make sure that those photos are in Aperture and not the folders. Should I just put them into iPhoto11?

I can't seem to resize photos in either - is that right??

I'm using Aperture largely to smarten up some photos for a web site. I want to then make thumbnail size photos of the same things, but I need thumbnails to be specific dimensions (133 x 199) and neither program seems to be able to do this.