The Molotov Plan is pretty straightforward. While the Marshall Plan was, in part, created to stop the spread of communism, the Molotov Plan was there to encourage it. Money from the Soviet Union could be used to prop up nascent communist states in a similar way that the money from the Marshall Plan was attempting to rebuild western-style democracies.
In terms of which one was more successful, look at the list of Molotov Plan countries. Not a single one of them is still communist. However, the countries the United States helped out are doing great and are among our most loyal allies.
The Morgenthau Plan (named after Secretary of the Treasury, Henry Morgenthau) was created before Germany surrendered, but after the writing was on the wall that Germany was going to. Essentially, the idea was the opposite of the Marshall Plan.
The most important part from a military strategy standpoint was the removal of Germany's ability to wage war. If this meant destroying its economy, that was totally fine. Germany was going to be cut in half, all of its industrial machinery closed, and industrial centers either given to neighboring countries or just to the world at large.
Oh yeah, and the person in charge of the country would be a military governor who could pretty much do whatever.
Really, the Morgenthau Plan didn't end up being that important in the scope of history. It was replaced by JCS 1779, which dialed back the putative parts of the Morgenthau Plan with an aim toward making Germany stable, productive, and not doing the exact same thing that led to Hitler's rise. From there, they went to the Marshall Plan.
As for why all the plans have M names? Total coincidence. Weird though, right?
U.S. foreign policy from about 1945 to 1989 revolved round fighting the Soviet Union without actually fighting the Soviet Union. There are two reasons for this. First, both Napoleon and Hitler proved that invading Russia is only slightly more productive than hitting yourself on the head with a hammer. The second is that the Soviet Union got nuclear weapons in 1949 and any war would be the apocalypse.
If the Marshall Plan was the opening salvo against the Soviet Union, President Reagan presided over the end. Some will say that he singlehandedly won the Cold War, but it's more accurate to say he built on what others did.
Under Reagan, the plan was spending. Essentially, the US kicked military spending into high gear, producing tons of both conventional and nuclear weapons. The Soviet Union had to keep up, or they could be annihilated. Whoever could spend more would win. That was the U.S. The fallout of this, unfortunately, was a ton of nuclear weapons in a state whose government was falling down around its ears.
But, hey, no more Soviet Union.
The main significance of the Reagan Doctrine as opposed to the old model as this was a shift from the accommodation of Bohlen or the containment of some other thinkers. Reagan was all about rollback. He wanted places that were either communist or socialist (he didn't always differentiate, even though there's a vast difference), to not be.
This created one of the largest features of the Reagan Doctrine: the support of right wing guerrilla armies around the globe who were either fighting the Soviets or any kind of communist, socialist, or left wing government. This included the Mujahideen in Afghanistan, the contras in Nicaragua, and UNITA in Angola. Effectively, this made the U.S. involved in the civil wars of other countries, either supplying money, materiel, or training to whichever side was more right wing.