Ah, great! The multiple physical locations part is key for the multiple listings. You should be good to go in listing each.  Cheers!

Google's guideline is here: https://support.google.com/business/answer/3038177 with the most applicable portion  being in the address section:

• Make sure that your page is created at your actual, real-world location.

• Use the precise address for the business rather than broad city names or cross-streets. P.O. Boxes are not considered accurate physical locations.

• If you need to specify a mailbox or suite number within your physical location, please list your physical address in Address Line 1, and put your mailbox or suite number in Address Line 2.

• If your business rents a temporary, "virtual" office at a different address from your primary business, do not create a page for that location unless it is staffed during your normal business hours.

So his locations need to be staffed, open to the public, office based locations. If he's serving clients in 4 different cities, but only has one office in one city it's not the same thing as the requirements above. That would be, "Service-area businesses--business that serve customers at their locations--should have one page for the central office or location and designate a service area from that point. If you wish to display your complete business address while setting your service area(s), your business location should be staffed and able to receive customers during its stated hours. Google will determine how best to display your business address based on your business information as well as information from other sources. Learn more about service-area businesses."

The document as a whole is worth the read. Cheers!

Hi Rosalia. Keywords are typically determined at will, meaning, if you want to rank for a the keyword "lizards" you make the best page you can about "lizards". Keywords also can be determined via the search engines, meaning some people arrive to your site in with terms that might surprise you. Ideally you're trying to find a sweet spot where you're getting a decent amount of targeted visits from people that are interested in what your site has to offer.  As a working example, visit Wikipedia. Basically each page of their site relates to a keyword that is the topic of their page.  Make sense?  Cheers!

Great update Miriam. There are a lot of things site owners can add to these types of pages to help with unique content: drive time to the nearest branch from City / Neightborhood X; mobile service schedules in City / Neighborhood X; Images of service radius; highly localized testimonials, etc. Will be interesting to see the impact with franchisees..

Doubtful. Several sites mentioned on their clients page are showing numbers in OSE.  Try out a few from: https://sucuri.net/clients/.  Chances are you have a robots.txt issue blocking OSE, the site is brand new, or it's on a tld domain that is currently not compatible with OSE, such as http://example.website  If you list your site here more details could be provided. Cheers!