Who is invited to give a talk at the reception? Professor Richard Johnson from______.

Good evening, ladies and gentlemen,
    A warm welcome to you all to this reception. First, I’d like to say a few words about tonight’ s program. (11) We should begin with the talk by Professor Richard Johnson from London. (12) This will be followed by a question and answer period. You would be free to exchange ideas with the professor. (14) At about 8 o’clock tonight, when the talk finishes, the reception will go on and (13)we have prepared some chocolates, drinks, and foods outside for you. (15) The professor is taking his flight home tonight although we would like to have him here longer with us, We’d have to make sure that he leaves here by 8: 30.
Questions:
11. Who is invited to give a talk at the reception?
12. What period will follow Professor Johnson’s talk?
13. What refreshments have been prepared outside for the guests?
14. When will Professor Johnson finish his talk?
15. Why must Professor Johnson leave by 8：30?