不知道F1学生可不可以开户呢？需要去Local Branch开还是online就可以啊？

Online is ok. You don't need to be PR.

另一个问题就是，Roth IRA和Traditional IRA到底哪个好一些呢，^_^

Well, In a nutshell, traditional IRA is tax free for now, while Roth IRA is tax free  when you withdraw. So it's hard to say which one is better.