Q4. What Du’aa should I read when I’ve sighted a new moon? 

Bilal Shah,

(Croydon) 

A. Allahu Akbar. Allahumma ahillahu 'alayna bil-amni wal-imaani, was-salaamati, wal-Islami, wat-tawfeeqi lima tuhibbu Rabbana wa tardha. Rabbuna wa RabbukAllahu 
 
Allah is the Greatest. O Allah bring us the new moon with security and faith, with peace and in Islam, and in harmony with what our Lord Loves and what pleases Him. Our Lord and your Lord is Allah. (at-Tirmidhi 5:504) 

(VERILY, ALLAH TAA’LA IS ALL-KNOWING!)