First person pronoun

I have a few questions!
So, I've heard that it's okay to use "ore" with friends
1) Is it the same for friends of all age groups?
Senior or junior.
2) Can I use it with both male and female friends?
3) Can someone use it with their family members?
4) Do I start talking/chatting with someone using watashi when I first meet the person and can I later transition into ore if we become friends?
5) Is watashi too formal and only for business settings?

by Reasonable_Leg_5433