Showing that you have done some research to find out your application loads and therefore mentioning the minimum required requirements is a good thing. Remember though that the golden rule for the exam is to justify each choice so if you decide on a server
you should indicate why you chose it over others.
You
can suggest cloud deployment but (again) as with everything, justify it, and not just with general cloud vs non cloud reasons, but reasons specific to your scenario. Sometimes the (generally) best approaches can't be chosen for a project because of the nuances and specifics of the scenario. The exam is about
testing that you can chose the closest applicable solutions and are able to justify why you didn't chose other solutions which another person might have chosen. The perfect solution for the assignment justifies every decision by mentioning at least two other alternatives and why they were not chosen over the one you chose.
For the component diagram, you can indicate other components that you didn't model in your class diagrams (e.g security pages, auditing modules, JAAS modules) . Some of these you may have mentioned (but not modeled) as packages in your class diagram. Remember to mark the integration strategies between your components if they are in different layers in your assembly connectors.