Thank you for your question
My name is Clare
I shall do my best to help you but I need some further information first.
Have they confirmed that she is willing to take up the Deputyship?
1. The wording reflects the point you made in your letter that this is a modest estate which needs to be administered
2. No she cannot claim costs from you - only from your mother's funds - as can you
3. Yes that is the way that is is presented
4. Yes you can withdraw at any time
I suspect that the understandable hurt you must feel about your sister's actions has made you very sensitive and because of that you feel attacked because of the very formal legal language used.
Please do not be concerned at this point - wait and see what "conditions" are actually made
Please ask if you need further details