To improve you viewing resolution choose View > Display Performance > High Quality Display.
Two more resources to learn InDesign:
(a) Sandee Cohen's excellent and inexpensive "InDesign CC QuickStart Guide" from Peachpit press. It's the best book for beginners.
(b) David Blatner's "InDesign CC Essential Training" video course on Lynda.com. You can get 10 days with a free trial.
Is this a function of the massive down-sizing?
No. When you place an image a JPEG proxy is created for the preview. Check View>Display Performance, which will affect the quality of the proxy view.
InDesign doesn't do any resampling, it resizes or scales the pixels. You do have the option to lower resolution when you export to PDF, but in your case you will need all of the image resolution—7276 pixels at 24" would be 303 pixels per inch, which is what you need for most high end print work.
10.52 MB is actually quite small for that size image. They must be saved as JPEGs?
Principle photography is now complete and I just got the pictures back and they're enormous (one pic alone that will print across two pages has dimensions of 7276 x 4856 - 30.0" x 20.2" and is 10.52 MB in disk size).
The saved "dimensions" of 30.0 x 20.2 are actually irrelevant (and indicate the saved resolution is about 240 ppi). What counts is the "Effective Resolution" -- the resolution at the scaled size you will use for output, and scaling this image down to 24.25 wide (your full spread plus bleed width) gives you a more realistic (for a coffee table book) 300 ppi effective resolution. You wouldn't want an image any smaller than this.