Congrats on being a grandma! I'm so sorry you got the other news though.
Three of my sisters have had breast cancer of varying degrees of severity. One sister had a lumpectomy about three weeks ago and is getting ready to start radiation next week. Her tumor looked to be 1.5 cm before surgery but was actually 3 cm. She just got the results from her ONCA test and she's in the low range for recurrence so she doesn't need chemo. She was back to work in 2.5 weeks.
Another sister had stage 3 breast cancer (lymph node involvement) and grade 3/4 tumors in both breasts. She had a double mastectomy in December 2011, followed by chemo then radiation. She is also a teacher. At the time she got her diagnosis, she was running and walking regularly and training for her second half marathon. She had her surgery after school got out for Christmas break and finished treatment seven months later.
She couldn't work while she had chemo so she didn't go back to work until fall 2012. She was teaching first grade at the time and it was simply too physical for her. Her oncologist was also worried about all those germy kids so he was opposed to her working at all. I think if she had a desk job with adults, she might have been able to work part time during chemo (i.e. no work on chemo weeks and partial days during the non-chemo weeks) but it would have been 4-6 weeks after surgery that she would have been able to go back. (Your doctor can tell you how long. It has to do with when you stop pain meds and how soon you have mobility in your arms to drive.)
The drains were a pain. She had a couple tank tops with little pockets to hold the drains. Showering, she just did the best she could. She definitely didn't shower every day because changing the dressings was hard. Since you're married, you might want your husband to give you showers at first. I personally wouldn't worry about shaving my legs. You'll need help with that at first anyway because you probably won't be flexible enough to do it yourself.
Good luck with everything. I think the most important thing to know is that everyone is different. Some people have a really hard time and others go about their lives with no problems at all. Just remember to listen to your body and don't do more than you can handle.