Nobody in the GOP is arguing against repealing Obamacare, even Paul Ryan. It’s the fact that so many want to replace it with something and the various train wrecks under discussion that are the points of disagreement.
Sure, and particularly in the Senate, which is where Cruz would play an important role. He’s the one saying “repeal every word”, and there are others with more moderate views who need to get together and work out a soution that will meet Trump’s requirements (actually address the root causes of healthcare costs) and that a majority will vote for. Including some Democrats (well Manchin, at least). This is how the process is supposed to work, imagine if the Democrats had actually worked with Republicans in the first place...
Because of the strong R majority, the House can pass most any crap and yet nothing will change unless and until it’s a bill that the Senate will pass and Trump will sign.
Negotiation.