The clearaudio concept clamp is obviously the best cosmetic match for your table. Nonetheless I find it to be very light, so I'm not sure if it's really doing much. The record weight from
Project is a pretty good value at under $100 and is a lot heavier.
As to whether it will make the table run slower, yes, if it has any substantial weight. You should be checking and revising the speed on your concept turntable though. One of the great things about that turntable is the ability to adjust and correct the speed ( with the speed adjustment pots at the back of the table ). There are free though somewhat crude turntable speed apps for Apple iPhones and android phones on their respective markets. What I like to use is a test record from Dr. Feickert that has a 3150 Hz test tone. You then download the free app called Platter Speed from the Apple App Store. With those two things you can very accurately measure your turntables speed and stability. This is what Michael Fremer and the stereophile guys use that you see in the magazine.
Of course a good dealer would have done this for you when you bought the turntable from them if you had them set it up. In any case these are still good tools to have for any higher-end turntable owner.
As for the impedance and gain settings you should use, these will depend on whether you bought the Concept MM or MC cartridge. For The MM, it's the same as for all MM cartridges, which is 40 DB gain and 47K loading. If you bought the MC cartridge, the gain should be at maximum, which is 60db on that phono stage, or all the dip switches in the up / on position. The recommended loading is about 100 ohms. The closest to that on that phono stage is 121 ohms. Nonetheless, some of my coworkers actually prefer a higher loading, in this case 1000 ohms. I suggest starting at 121, the try 243, 475 and 1k ohms and listen to see which one you like the best.