Alice,
I saw your questions and while I can't answer all of them from personal experience I will throw out there what I can and hopefully others will join the conversation. (Disclaimer: when I say you or you're I mean it in a general sense, I did catch that you were asking for a friend.
)
The reason radiation would be important is because she is having a lumpectomy. When I was diagnosed I was told that with a mastectomy I may or may not need radiation but with a lumpectomy the risk of recurrence goes up significantly without radiation so my takeaway from that was that it's a critical part of treatment if you have a lumpectomy.
Herceptin is a targeted drug for HER2 cancers and while everyone is different, my understanding is that herceptin alone is more likely to have a positive result than chemo alone. There may be a reason the doctor is not recommending chemo and it never hurts to ask that question, just so you know what's going on. Doctors handle these situations every day and I think they sometimes forget we don't have the educational background they do so if you're unsure about something they're telling you, you should ask. If they have a problem with that then I would consider getting a different doctor to be in charge of my medical team.
I hope that helps some.