Biting and bumping ?

[Torosum]

Hi Everyone,I have a cat which is 3 months now.I love too much him and he loves me too much but He sometimes bites me.Generally I can touch and love him he kiss me and he loves me I know but when he has full energy he bite me , when he stop to bite ? Is it about his teeth ?
When it will be finish


Another question
My cat plays too much and he bumps his head everywhere and I scare it.IS it normal ? Is it a dangerous

And lastly

He sometimes smells my genital ( after shower , after wc ) I scared he will bite is cat biting there ? If cat will bite there is it dangerous ( any damage )


Thank you too much
My English is not well sorry