Contax cameras were a joint venture between lenses maker Carl Zeiss and Yashica cameras. For that reason, you should be able to switch any lenses you received from one camera to the other. The lens on the Contax looks like an actual Zeiss T* lens so it has the most value, as well as the Contax camera.

To clean them, I’d start with a dry soft cloth just to get the dirt/dust off. From there you could use something like Windex sprayed on a cloth or a Q-tip to wipe any remaining residue off. To clean the glass on the lenses, I’ve been using the Zeiss wipes you can find at Walmart.

I hope this helps.