1) <a4j:htmlCommandLink> should be applyed in VPE only inside <h:form>, <a4j:form> or inside any component, that is situated inside forms. <a4j:htmlcommandLink> doesn't even appear in source code of a page in browser, if we try to exclude it from any form.
2) If we try to use <h:commandLink> outside forms, next string appears in browser: <Our Link>: This link is disabled as it is not nested within a JSF form. But VPE renders it OK.