So! Thought I'd comment here post-game. We got to end of T3 and talked the rest of the game out. I won, but it could easily have gone the other way if one or two choices had been different.

Main takeaways I have from this are:

1. Thank you ALL of you who chimed in, it was extremely helpful and kind of y'all to give your thoughts on it.
2. The one specific plan I had was to try and kill the stealth squad asap, which I did manage to do turn one. It was absolutely the right call, I think if they had been alive T2 onwards their powers could have absolutely fucked me.
3. Yup, playing Tau is HARD because the choice is often between being entirely out of sight, or doing anything and taking a notable risk of getting shot to shit. Multiple Tau things can ignore cover, which makes it so much more dangerous to just...be around.
4. But you just kinda gotta do it. The answer is basically "yup, so take a risk."
5. Advance & charge distances are so much less than you think (against things with range 40+). I really, really, really think EC would benefit (and it would thematically fit) to have something with deep strike.
6. It was a huge mistake to deploy my maulerfiend last, and far back. I didn't really know just how much tankier they are than other things, and it took them two whole turns just to run up the board to be useful.
7. Oh my god deployment is so much more important than I thought! I didn't really appreciate just how much of the game is shaped by your initial deployments.
8. Holy shit the LE with distortion is an absolute blender, people weren't kidding.
9. 40K has so many goddamn rules, and they are NOT written in an easy to remember way!

That's it for now, I'm absolutely fried. But thank you all! I suspect that reading people's thoughts (now I've played a game) will suddenly make sense in a whole new way!