Yes, you can use text style signature as SigPool system will automatically convert it to image.
Yes, you can. Every banner can have different link.
Yes, you can. We call it banner ratio. You can enter banner ratio from 0 to 100. Bigger ratio banners has more chance to be showen. If all or few banners ratio are equal than they have same chance to be showen.
Yes, you can GEO target banners as you want. You set for which country to show or disable each banner.