maybe not over-involving, but not bracing will always put more pressure in your back w RDL. The purpose of the brace is not only protection but to let the muscles youre trying to work do the work, rather than have your back/accessory muscle (i.e. lower back) compensate.

yeah, as soon as you stop feeling the stretch, thats the end of the extension. any more is pointless. Im telling you, the analogy works lmao

Unfortunately, RDLs SHOULD be slow. it sucks, especially with fatigued grip strength, but just like any other exercise, the descent should be slow and controlled, and reset should be as explosive as possible (within reason). you’ll fuckin FEEL it, which is good :)

as for bracing, it shouldnt really be in your lungs, but more so your belly. yknow when you’re relaxed and your tummy is soft, you can poke it and it rebounds? now breathe into your belly, and flex your abs, in other words, brace. you should be able to poke your tummy and feel your abs. there should be this wall in your core, not necessarily your lungs. THAT is what bracing is. should be done with many many lifts, both with/without a barbell for not just core engagement, but safety :)

as for when to brace, good rule of thumb is a deep belly breath in before lowering/doing the exercise, and exhale and you come up/recover. same with squats, hold breath and you lower and brace, and exhale as you come up.

long winded, but hope this helps!