I'd never tell someone I was interviewing if they'd got the job, or not, at the interview. I'm fairly sure it's uncommon to tell a candidate straightaway.
I stand to be corrected/shot down in flames, etc.
+1
I expect it depends on the job and the company but I am an engineer in a large company with a fair bit of recruitment experience and we never tell candidates at the interview the result. I have been interviewed by a number of companies and again never had feedback there and then. In the case of the OP I would imagine there will be a number of applicants (possibly interviewed by different people depending on the size off the company) so they are unlikely to tell at the time.
To answer the OP:
Have they told you the format (Normal interview, Psychometric Testing, role play etc)? If it is competency based which is quite popular in large organisations then try to think of examples from school, university or part time jobs to demonstrate the competencies they are looking for (normally things like Team Working, Focus, communications skills etc.) Sometimes they will send you information so you can prepare a bit.
Relax (easier said than done)
Don't worry about short silences (either to compose an answer or after you have given one) and don't try to fill them!!
As others have said, have some intelligent questions prepared for the end when they will ask you (Long term career opportunities, do the encourage charter-ship, structure of their GDP etc rather than pay and holidays!!). If they don't ask you then ask, but don't try to get them in mid interview unless they are naturally drawn out in the discussion.
You never get a second chance to make a first impression - cheesy but true - they are looking for someone who in a short time will be representing the company with Customers and suppliers - you may get away with looking like Wurzell Gummage if you are an expert on something and there is a skills shortage but you aren't and there isn't.
Read up on the company, its market position and its competitors.
They will be looking for enthusiasm, intelligence and potential at this stage, but it will help if you could tell the difference between a transistor and a resistor if asked
Best of Luck