What not to say? Anything that would be a lie - esp. RE: your medical history (drinking, drugging, smoking, liver problems, clotting problems, etc). Just be honest with your Endo - think about your current/short-term goals of HRT, and be honest about your long-term goals (if you know those already). The Endo knows that things can change along the way (esp. the long-term goals), so there's really no point in omitting what you're aware of at this point in your journey. Keep working with your therapist and your wife to hash out your goals. Long story short - just be honest and open with those involved in your journey.
I"m also from Texas, so I know all about the heat (from the Gulf-coast muggy to the West coast dry/oven heat. I've not had an issue with my breasts - mine are developing (slowly...38AA/36A). I do have an athletic frame, so they somewhat merge into my overall physique, but they jiggle up flights of stairs, and I can tell when someone is staring at them. When I need to squash them down I use a tight undershirt and a slightly bigger button-up at work; on the weekends, a sports bra (with wide bands) under a T-shirt. Since TX loves their AC units, anytime I'm inside (coffeeshop, store, etc), I usually have a thin sweater to cover up even more.
I've never understood the 'brain fog' insinuation. If that were true, than that would seem to justify a perception that cis-gender women are intellectually sub-par compared to cis-gender men, which is patently false. Maybe cis-gender women analyze problems differently than men, but that's not brain fog. Nevertheless, I've not experienced any decline in intellectual capacity since starting (almost 2 years), and I work in a highly technical/analytic field.
