From your cloud manager  click on Environment and there you can click see developer console. 

You can still use it but only thing is for every change you need to push the code and deploy in dev as well .As you cannot edit /apps in AEM as a cloud directly from crxde.https://experienceleague.adobe.com/docs/experience-manager-cloud-service/content/release-notes/aem-cloud-changes.html?lang=en 

After stage testing step is it keep going till deploy to production? 

Can you share the snapshot , as approval is required for production deployment.

Check this for precedence https://experienceleague.adobe.com/docs/experience-manager-65/deploying/configuring/configuring-osgi.html

Good one