2: Yes, if you look at the CS we provide a template for on the OoC, you'll note there is a custom jutsu section. Make whatever you like, as long as it isn't some ridiculously overbearing world destroying technique. Whatever you make, we'll be sure to look at it closely when you submit it, and tell you if it's good or not.
3: You can, if you can explain what a samurai is doing in Konohagakure. Anyone familiar with canon will tell you samurai tend to live in the Land of Iron, so you'd have to come up with an explanation as to why he lives in Konoha instead. It's all well and good if you can, in fact, that kind of creativity is encouraged, but it has to make sense.