Help with promotion discount needed

How do I select products that have a specific feature, eg. a specific manufacturer; and set 20% discount for these products under Cart promotion.

Manually add products into the product list under bonuses or conditions are not preferred as the product list will be changing with new products under the manufacturer being added. Furthermore, the number of products might go up to 1000 or more. And the promotions’ product picker do not allow me to search by features.

Setting it under Catalog promotion is not feasible for me, as I have other Cart promotions like discount coupons, membership discounts, and I would like that only 1 promotion is applied on a product at a given time (eg. either the 20% from the manufacturer promotion, or 20% from a coupon code promotion, and not 20%+20%=40% off due to two promotions being applied).

From what I can see, cart promotions cannot stop Catalog promotions rules. And vice versa.

If anyone can help me with this, I will be most thankful! ^^