Advices for a future rabbit owner !

Hello r/rabbits ! I’m gonna adopt a rabbit very soon ! I read many blogs and books about buns to treat my future baby the best in its new life ! But I wish I could have some advices for beginners because I want to make 0 mistakes! Also I have some questions :

Is putting the litter in its cage okay ?

I want my bunny to play outside, in my garden of course with a leash and under my guard, is it okay ?