My Mum had a lumpectomy and node removal in March. Her drain fell out next day (some would say lucky!) and it was not a problem and has not been a problem. The other women on the ward did vary with their drains but most of them had them taken out before leaving hospital (5 days) so I am amazed that people seem to have had them in so long. Guess everyone is different.
The main thing with my Mum was her positivity. She made a very fast recovery because she was not going to let it beat her. She made sure that she stayed active socially (retired so did not have to return to work) and did things she enjoyed. She was very concious of doing the lymph fluid exercises so the lymph drained from her arm properly (can't remember what they are called). She had a course of radiotherapy and then went off on holiday. She has decided not to take chemo (they said she could decide, take it the stats on do and don't must have been similar). As for pain, again there was some but she kept a smiley face on it and didn't let it bother her.
It is very hard to support someone going through this but I just remembered to be normal and make her smile and laugh to help the healing. I am lucky that my Mum was so positive in herself. Make sure your Aunt uses the support people on the ward - some have previous patients that pop in and do massages, manicures etc.
Through my work I have a good insight into the NHS and knew that to get answers you have to fight a bit. Make sure that you push people to get the best treatment available, don't be afraid to ask. (I attended most of my Mum's appointments so I could ask questions that she may not think of).