Thanks for your review! I'm aware that they are not unique points. They all come either from hard experience or from things I've read from people I respect over the years.
It's not my first programming gig, and as for young, it's relative. I'm in my early thirties. Unfortunately, I am the most senior person there.
I am surprised my writing style would lead anyone to think I'm young. Are there any specifics there? I have taken professional writing courses, but writing is still something I try to improve. I will keep the suggestion of enrolling in one in mind, though!
That particular gramatical error was really a typo. Either way, if I decide to send it at all, I will definitely be proofreading it again. Even though I re-read it once, I missed that one and would probably have missed it every time.
I haven't provided examples for three reasons. First, I'm hoping it prompts discussion. Second, many of what I would include as examples are things that either I or they have pointed out previously. Third, it is already very long; details will bog down the pace. Given those reasons, would examples still help?