I've just started learning Bach's Siciliano through Kempff's edition. Since there are no fingering in the score I would like to ask my questions here.
Right hand plays the mid and high voice. High voice is legato and middle is scatto.
Are there 'rules' (suggestions) like I shouldn't play the legato with same fingers?
I'm not sure what you mean....are you talking about playing a legato line using only finger 5? I'd say if that can be avoided in any way, you should, because you will definitely lose legato. That isn't always possible, but if it's clearly marked legato then you should find a way.
Are Stacattos better of played with same finger considering they are more rhytmic?
I would avoid this as well unless absolutely necessary because whenever you move from one key to the next using the same finger, that's a place for potentially missing. Ideally, all fingering in stepwise motion goes from one finger to the very next finger. There are a myriad of exceptions to this, but whenever possible, you use the next finger.
Since it is the most advanced piece I have yet to learn to date I have my doubts start learning it blindly.
Since there are exceptions, you may want to post the specific passage you have questions about. That way you can get better answers.