I agree with most of what you wrote in last post, but I strongly disagree with Dr. Rais assertion
"the prime minister is simply the first among equals [the cabinet members]; they all rise and fall together.”"
They don't all rise and fall together and PM is not simply first among equals. All or some of the cabinet can fall without causing PM to lose his/her position. While, if PM stops being in the position of premiership, all of the cabinet members automatically lose their position.
Also, in the areas where constitution is silence and PM is specifically mentioned, no one other than PM can perform that duty. This was the case about the budget, approved only with the presence of PM and his signature.