Well then the other question is, if I used Aperture could I do it all with one program?
LR and Aperture perform quite similar roles. LR is modal -- there are certain screens and areas for doing certain things (e.g. you can only do the heavy lifting for editing in the develop pane). Aperture is decidedly *non* modal -- you can pop up the editing HUD and edit a photo *anywhere* -- even on a screen where you're looking at the web page output. Some people prefer one way of working, some another.
But both LR and Aperture do organization, the enable rapid editing and culling of images, along with quickly finding "selects," etc. But neither has the editing power of Photoshop Elements or Photoshop. But for many people, what they offer is sufficient.
Best advice I can give is to try them out and see how they work for you. Both products have 30-day free trials. If you're on a Mac you have the luxury of using either. If you're stuck with a PC, well then you have but Lightroom as an option.