1. Read your manual.
2. Why should we tell you what picture style to use? It's entirely up to you, up to the effect you want, up to the situation, lighting, subject, etc etc etc
3. Any customized settings.... are UP TO YOU. That's one of the main reasons to get a DSLR, it's for you to have more control.
4. How should we know if your flash is not strong enough? For what situation?
Or are you talking about some picture that we can't see?