Hi Alissa! Welcome to the world of digital!
I have been in the graphic design industry for a few years now, and we use InDesign at work daily. InDesign is a great layout program - we use it to set up ads, flyers, programs, brochures, business cards etc etc. So you are right, it is a great program for layout design.
For all of my digital scrapping, though, I use Photoshop. The reason is this: with Photoshop, you have much more control over manipulating your photos, papers and elements. InDesign cannot fix red-eye, create a metal eyelet, recolour a pre-made element or change a photo to black & white instead of colour. You have so many more options for scrapping with Photoshop.
If you were to use InDesign, I would think you would ALSO need Photoshop. You could manipulate your photos and elements in Photoshop, then save and import them into InDesign, where you could arrange them on your page as desired.
Also, if you were to send your layouts to be printed via an online photo service (or put them on a disk and take them somewhere to get printed), you would then need to save the InDesign layout as an eps or PDF, then open it in Photoshop and save it as a jpg.
Hope this helps!