Friends can be amazing support but they can also be quite draining if all you're talking about is cancer. What worked for me, and it's not for everyone, was letting a couple of close friends tell everyone else but with the instructions that they weren't to call me - they were told I was hunkering down and that any info would be passed on. A few weeks later, I started a blog to update people. What this all meant was that I didn't have to make excuses for how I was feeling (and sometimes I really wasn't there if you know what I mean) but that I didn't feel like I was having to cope with their feelings all of the time. And I certainly felt the love as I was going through treatment - even calling in to work (like you, at a school), colleagues would make small remarks that showed me they were following my progress and were supportive but without weighing me down.
As for appointments, I retained some of what was said, but would somehow vague off for other things so it helped having someone else with me. I did, however, learn early on to write down any questions so that I would forget to ask.