Simple Nikah

A3: Yes, the presence and consent of the bride's Wali and two adult Muslim witnesses are fundamental and essential conditions for the validity of any Nikah, including a Simple Nikah, according to Islamic law.  
A2: Absolutely. As long as all the essential pillars and conditions of Nikah are met, a Simple Nikah is fully valid in Islam. The simplicity of the ceremony does not diminish its religious authenticity.  
A1: "Simple Nikah" refers to an Islamic marriage ceremony that focuses purely on the essential religious requirements for a valid Nikah (offer and acceptance, Mahr, Wali's consent, and two Muslim witnesses), without additional customary or elaborate elements often found in larger wedding celebrations.