Is the prayer invalidated by reading "dhāl" (ذ) by pressing the teeth together, making it resemble the sound of "zāy" (ز)? And is it necessary to disregard the whispers of wind in ablution, even if they lead to the rejection of intention?

Waswasah (obsessive whisperings) is a chronic disease, and its cure is to ignore it and pay no attention to it. Waswasah regarding the articulation of letters and pronunciation is one of the gates of evil that scholars have warned against, because it deviates the worshipper from the proper etiquette of prayer and preoccupies him with exaggerating the letters instead of understanding the recitation. Therefore, Al-Fatihah should be recited normally, without affectation, while being careful to pronounce the letters from their correct articulation points without exceeding what is obligatory. The word "الصراط" (As-Sirat) is pronounced with a "ص" (ṣād). Some of the seven reciters (Qurra' Sab'ah) recited it with a "س" (sīn), and some with a "ص" (ṣād) mixed with the sound of a "ز" (zāy), and all of that is permissible. As for the "ذ" (dhāl) in "الذين" (alladhīna), it must be pronounced correctly. The cure for waswasah in ablution (wudu') is to ignore it. So, no matter how much Satan makes one imagine that something has exited or that the intention for ablution has been rejected, one should not pay attention to these whisperings.