test of links in a domain ?

Hi,

As I understand it, "web accessibility" allows you to specify a set of standard "web page element" tests for a given web page.  The "check links" option appears ideal for me, except that our web pages are still being developed, so that I'm getting failures because some of the links are not defined yet. Is this correct?

Yes, it is correct. You can use the Check link accessibility option of the Web Accessibility checkpoint to check whether all links on the page are available.

As I understand it, "web comparison" allows you to test that the HTML of a page matches (at different levels - compare entire page, compare tag structure, compares specified tags ) the HTML of the stored object.  This may work for me, I will have to experiment further. Is this correct?

Yes, it is correct.

The object checkpoint lets me group objects and properties and run a single check or comparison, so as you suggest it would be a matter of selecting the parent object (presumably the entire web page) and checking the child objects (links) with their properties..... This also has possibilities.

Yes, it is correct.

Is there any way to automatically "crawl" all of the links within a specified website, so that I'm not manually navigating to each page?

You can record a test that will automatically navigate to the web site's pages and check the links accessibility on each page. That is, you need to perform verifications for each page.