After you open Support requests tile you will be able to see all cases, created from this account, their number, status, severity, date of submission and last update date:

Yes, you can filter your cases according to status - new, open, solution sent or closed:

To review information regarding a particular case, click the + sign next to the case number. You will be able to see full case status, updates in the Latest on the issue tile and case history:

An update to a case can be sent as a comment. To leave a comment click the + sign next to the case number and scroll to the very bottom of the window. Fill in the comment then and attach a file if necessary (note that the file size limit is 5 Mb):

The comment will be recorded in the case history and will be processed by the responsible Engineer. 

Yes. Scroll down to the bottom of cases' list and press Submit new case button: