The site below has a "self-evaluation" that can be used as the first step toward diagnosis. The test results can be printed out and taken to the doctor. The fourth question may be the most important one. An apnea sufferer will have periods of snoring, then stop breathing and suddenly gasp or snort. Have you observed this with your husband? This is an apnea and should be reported to the doctor. As I said in my post, while not all snorers have apnea, all those with apnea snore.
You asked about the "first line of testing" - that is generally an interview to assess whether a sleep test is warranted. The doctor should ask many of the same questions (and probably more) shown in the "self-test". If a sleep test is warranted, it can often be done at home. The patient has a cannula (to determine the breathing pattern), sensors to monitor the heart, and a fingertip oxygen sensor. The results are examined to see if apnea is present with a AHI (apnea-hypopnea index) rating. If the results indicate a CPAP is required a second test will determine the settings.
The self-exam is found at http://www.sleepapneainfo.com/sleep-apnea_l2.php?id=91
Note that similar tests can also be found at other Internet sites. Hope this answers some of your questions.