Pagans in general (Wicca is just one branch of Paganism) believe in deity in many forms. Satan, however, is a construct of the Abrahamic religions and pagans do not believe in him.
Yes. Wicca/Paganism allows the person to believe what they wish as far as God vs. Gods. The name they wish to place upon their deity. The only real rule is you do not harm anyone (yourself or others).
Some Wiccans do. This is left to each individual to determine. Some perceive supernatural events and hidden "powers" to be those which can be cultivated. Others perceive these to be flowing from God....
Of course it is - one doesn't make much sense without the other.
Yes,
It is OK, since God did make Satan. If you are a Christian of some sort, Satan is always going to be the one trying to wreck...