So sorry to hear this. It's a horrible journey to be on.
I had endometrial cancer in 2019, requiring hysterectomy etc, but luckily only needed radiotherapy to "mop up" afterwards. I was back at work about 3 weeks after the op, but still taking things easy. Although mine was keyhole, it's still surprising how knocked out I was by the surgery - the cuts on the outside aren't visible, but there's lots on invisible chopping about internally to heal from. And I didn't have any of the bowel stuff you mentioned, so take the time to recover physically.
I worked throughout the radiotherapy, but that's very different from chemo. Not as debilitating, but you do have to go every day for 28 days. I felt fine, just spent ages in the car! But it was important to me to work whenever I could, partly just to feel normal, but also because the company were (and have always been) very good to me and supportive. You will have to see how you feel, and you are protected if you need time off throughout treatment.
I'm 6 years clear now.... hooray. There is light at the end of the tunnel....
Regarding kids - my 3 were mid-late teens, and choosing the right time to tell them was the hardest thing. I decided not to say anything throughout all the weeks of investigation/diagnosis, mainly because I wanted the whole picture before informing them.....and boy were they pissed off about being kept in the dark! I broke the news just before my op, and they were adamant that they should have known sooner, and they were old enough to handle the whole "is it, isn't it?" process. I still believe I was right to wait until I had answers and knew what I was dealing with, and could give a positive story. And selfishly, I wanted to navigate the stressful diagnosis alone, without the "noise" of having to support them too....particularly if it had turned out to be benign - what would have been the point of worrying them for nothing? Sometimes you have to make unpopular decisions, so I only told them once I had no choice. To be honest, once they were told they were brilliant, and great support during my recovery, particularly when I was rushed back into hospital 10 days post-op with a haemorrhage.
Anyway, you are now approaching the stage where you need to tell them, as you really can't hide chemo without worrying them even more....you'll probably be surprised at how they handle it, particularly if you can give them a good prognosis. If you are worried they will feel you mis-led them, maybe a white lie that something was found during the op, blah blah blah. Definitely tell the school so they are aware.
Good luck.