Questioning Allah Ta'ala's decisions

Q: One of my Hindu friends asked how God decides if someone will be wealthy and others will be poor. Similarly, how will someone be born healthy and others disabled. etc. Is this decision randomly made by God or is there some logic behind it? I understand this life is a test but why do some people have relatively easy tests and others really hard tests?

Fasting till sunset

Q: "Eat and drink until the white thread of dawn appears clear from the dark line, then fast until the night falls" (Sayaqool:187)... I want clarification on this, in the Quran it is clearly described that fast until the night falls not the dawn falls out.