A few questions to web developers

Question

I would like to ask all of you developing website applications.
1) back-end vs. front-end application - why do you choose one of them?
2) what is your favourite programming language and why?
3) how do you decide what programming paradigm would you use in a project?
4) how do you choose between graceful degradation and progressive enhancement?
5) what database engine do you use and why?
6) which steps are necessary to ensure safety of a application?
Thank you all for answers and opinions

Answer 1

I was interested in a combination of answers by a man except the last question.

Answer 2

You should find answer of all your questions by searching in already asked questions :P