I personally don't mind the music, I know others do though. Dubstep you can always rely on but some people prefer other things. Some streams I watch play rap music, but if you have a mic, use it regularly, and set the volume to a nice level that just plays lightly in the backround, the music doesn't matter that much, it just adds effect. Dubstep is popular because most gamers enjoy or don't mind it.

Having a microphone certainly makes it more enjoyable and easier to interact with the stream. If you're just sitting and playing and not saying anything to your stream it can get pretty boring, and typing everything while playing is a hassel.

You'd start off faster by doing give-aways, but if you enjoy streaming, do it regularly, and stay to the same or a certain genre of games you'll gather a set of viewers that will slowly increase. Give-aways are always fun, sometimes even for the person giving away, but I don't think they're required to make a good stream. It really depends on what you want to do I guess.

These are my thoughts. Hope this gives you a better idea!