the page you have found is only a scratch how it should look in the future. Actually, w.r.t. to @RunAs annotation, it is quite an old scratch.
As for DRY, you can make an abstract class which has @Deployment(s) method, however you'll have to specify @RunWith into each of the (inherrited) classes. Yes, as you suggested this will lead to deploy/undeploy for every testcase.
As for ArquillianSuite, I'm not aware of any other runner than Arquilian, so suite is not supported. Can you please fill a jira containing summary of your question at https://issues.jboss.org/browse/ARQ ? This way we make sure that the SuiteRunner is a requested feature.