Freezing eggs?

I’m quite curious about the process itself and the affects of it as I may consider it when I’m older.

1)is it painful?

2)Do you still get periods ?

3)Can you still get pregnant or do they take every single one?

4)How much does it cost (uk) if it’s an available process?

5)Can you donate any for research or fertility treatments?

And any other information you can give me