Every person is different so whether she wants to talk about it is really her preference. Some people want to constantly talk about it, others not at all.
Having gone through breast cancer, chemo and radiation over the last year there are some people I could talk about it with, others not at all. I think the best thing to do is tell her you are concerned about her and want to do what will make her feel best. Tell her you are there if and when she wants to talk about it but if she doesn't that's fine. Let her be the one to bring it up.
If you do talk with her, don't tell her stories of people who have died or who have cancer. Don't talk negative. Keep everything positive that she WILL get through this. Treat her normal. Ask her how she is but ask her the same way you asked her pre-cancer. If she wants to elaborate, she will.
The person who upset me and stressed me the most through all this was my mother. She constantly wanted to talk about it... I didn't and told her that daily. She talked to me in a pitying voice and constantly asked me how I was feeling. Regardless of my answer she would continue to ask questions. If I said I was fine, then she'd go on to say, Oh you aren't tired? Well of course I'm tired, it goes with the territory but I'm fine otherwise. Daily I had to tell her to drop the subject that I don't want constant reminders that I have cancer.
There are people that I don't go near anymore because they are such negative people and always have a storey about someone with cancer, someone who has just died of cancer or some always negative cancer storey. I avoid those people because they thrive on negativity and these horror stories and I don't want to hear about it.
As for a wig, she may find she won't even wear one. I got a wig as I started to loose my hair and I think it's been on my head maybe 30 minutes total. Wigs are hot and scratchy. I've noticed most of the women who were a wig are older ladies, over 60. The younger ones mostly were chemo caps or went bald. Going bald is cold. Even at night in bed I wore a thin chemo cap or my head was cold and that is what most of the other women I talked with said they found. My favourite chemo caps were simple little cotton t-shirt knit caps. Being that I was bald in the winter, when I went outside, I put a winter hat over top. Chemo can also mess with your thermostat so you get HOT HOT HOT at times and a wig is not something you want on when hot.
Chemo is scarey and we have all heard horror stories of how sick people are. The anti-nausea drugs they have now are marvelous so tell her to make sure they give her anti-nausea drugs BEFORE she gets sick. I've heard of some doctors that wait until the patient is sick before giving the anti-nausea drugs but thankfully, the doctors here believe in giving the meds first to prevent it from even starting. Vomiting was my worst fear going into chemo but the worst I had was a few very minor twinges of nausea in the first couple days after chemo.
Exhaustion is a given and it is a complete physical, mental and emotional exhaustion and the most minor tasks become overwhelming. Chemo lowers our immune system and chemo patients cannot be around animal feces. I couldn't touch the hedgehogs for 5 months. I was okay with the cats but had to be careful they didn't scratch me and of course couldn't go near their litter box.
I guess the best advice I can give is to respect her wishes as to how she wants to deal with it.