بسم الله الرحمن الرحيم
(1) It is better to remove the impurity first from the impure clothes and then wash it together and if you wash them together and the impurity was removed from both types of clothes then too all the clothes became pure.
(2) In the state of janabat, impurity is unseen thus if a junubi person touches clothes then they shall not turn impure, however if the semen is smeared in the hands and that was smeared in the cloth etc then in such a case that part of the cloth shall become impure.
Allah knows Best!
Darul Uloom Deoband
This answer was collected from the official ifta website of Darul Uloom Deoband in India.