do all anime start from manga n so if it is succesful do most of the money go to the writer? (more similar questions inside) plzz answer

Well I'll answer as much as I can!
No not all anime start from manga. Sometimes there's manga after the anime, or there won't be manga at all. Anime can also start from visual novels, like (i think) Chaos;Head or Steins;Gate!!

Not sure about the money, sorry..

And I guess it's personal preference whether you want to do a manga or anime. For manga you sort of have more freedom, of what you want to draw or write and making your own characters could be fun, but it can be hard to get it published...
For anime you would most likely be drawing for other animes. So in their art styles and stuff (not too sure)

So yeah I hope I was sort of a bit of help! ^_^
(BTW you should read the manga 'bakuman' talks a lot about creating manga, and it's entertaining!!)