Being a learner Birdie Mum still, I can offer advice as I have discovered with Jo.

Shell grit - she doesn't mind it, had abit but generally just biffs it all over the floor . I put it in a separate bowl from her food.

Perches - I too have heard that the sandpaper ones are not good for birdies. I have natural branches along with one normal wooden perch, AND I have bought ones made from crushed shell, grit. Jo LOVES those and they come in different sizes so her feet do not cramp up on the little perches ........

As for house training a birdie. I believe you can do that, but Jo is not having a go at that at all! I am her slave ........