يلا is more commonly in all Arab countries
It's short for يالله it doesn't mean letterly (let's go)
but we use it as (let's go)
هيا بنا it's letterly mean (let's go) but it's not commonly now days because it's standerd Arabic
يلا بنا : Egyptions use it like يلا بينا
But if you use any of them they all make sence
You don't have to use بنا or بينا, as long as you're using يلا
يلا = yalla
يالله = ya Allah or yaallah
بنا = bena
بينا = beena