We often hear that anyone died on Saturday or Saturday shab consider not a good day to die and even consider Monday also a bad day to die. Is there anything that is being said about this? We know that we have to control on when a person will be leave this temporary world.

Also, I read that prophet Mohammad said that the day a person die, give sadka to save the person from wahshat of qabr and if you can’t do sadka then perform namaz e wahshat, want to know giving sadka is important or performing namaz?

Death is in the hands of Allah so no one can say anything about death time and day.
Yes sadqa has priority over first night namaz