He did not know that ghusl from janaabah is obligatory; should he repeat the prayers?

He prayed on his own and leading others when he was junub; what does he have to do?

She prayed when she was junub by mistake – does she have to repeat the prayers?

She wants to do tayammum instead of doing ghusl from janaabah because she feels shy in front of her husband’s family

He had an erotic dream whilst fasting but he did not see any trace of semen

He had a wet dream but he did not do ghusl because it was very cold