4. Yes, there is always a risk, but should we ban all risks? If so, we must ban all flying over built-up areas, so close most airports, incl LHR, Gatwick, Manchester etc. A step further would be to ban all transport including horse riding. Electricity can also be dangerous, so let's ban that too. Patently, those suggestions are ridiculous.
Sharpend - I suggest you read Satellite Driver's excellent post 121.
He points out very succinctly (and reiterated by others on this thread) that this accident was different in that people have been killed who had no connection with the airshow and who were therefore not deriving any benefit or pleasure from it.