Special as a Percentage of Base and Option Prices

I have a "Default" customer group and just created a "Club" customer group. I would like to offer Club members a 10% discount on most (but not all) products. This discount should reduce the cost of the product and the cost of each option. I understand that a special price based on the customer group is treated by eShop as a "Special" (and not as a "Discount," which is a quantity based price). The Special is created in the Product -> Special tab. A few questions:

1) Is there a way to specify the special price as a percentage of the Default group price?

2) How can the discount also be used to change the cost of options? The Special price seems to only affect the base price for the product, without an opportunity to change the option price. To give Club members the full 10% discount, the additional cost of any options should also be reduced.

3) Must this special price be entered product by product or is there a way to apply this special rate to all products (and options) and then modify any exceptions individually?

Wouldnt the easiest way to handle this be to give "club members" a special coupon code that only they have, which gives them 10% off all purchases? Coupon codes allow you to select which categories or even specific products it can be applied to. Coupon codes also allow you to set the customer groups that can use them, so if you add "club members" to a "club member" customer group as well, then even if non-club members find out the coupon code they wont be able to use it since they are not in the "club member: group.