The marks under the window are a sign of age. The edges of the rubber seals harden and can become brittle as a result of environmental deterioration. You would need to remove the window and replace the seals. If you plan on spending thousands making your car a mint show car then go for it, but if not, I wouldn't waste your money.
If the recaros are super clean, then they may be worth £575. I sold mine that were near perfect for £500 with ek9 rails about 2 years ago. Don't let they buyer tell you they are mint, decide that for yourself.
Dc2 rails can be made to fit. You need to cut and weld one of the mounting points. Some people prefer them as I believe they sit lower than ek9 rails. Otherwise you will need ek9 rails, or aftermarket rails for the specific seat and car (bride, spoon, recaro etc..).
Standard ej9 rails won't fit!! Just to clear any confusion from the above post.