Racism in Nepal and Caste system!

Kumaoni here , Recently got curious by Ethnicity of nepal....Like Here in India, Brahmins dominated the cultural & religious landscape I thought, nepal being hindu majority would also have same social hierarchy......but it is quite complicated there, I never heard bahuns leading the nepali culture by themselves......

Ques 1. What Ethnicity historically dominated the social hierarchy in Nepal?

Ques 2. I read mostly Indo-aryan(Newar & Pahari) are majority Hindus....but some Mongoloid groups like Magar , Gurung , limbu also have some Hindu population, do these groups have Caste system within them (like Magar Brahmins , Magar dalit , or Limbu Kshatriya etc) Talking about the Hindu Janjaati population!!!

And do Pahari & Janjaati groups mingle well or are A bit racist towards each other?? Do they marry within???

Anybody willing to clear my doubts can help 🙏