Just going from general history, the US high command (Joint Chiefs of staff) decided that Europe was much more important than the pacific and would devote 90% of her resources to the struggle (this later changed to about 85%). The US command believed that they could attempt a cross channel invasion of France in order to relieve pressure on Russia who was fighting to save Stalingrad at this point.

British high command (led by Field Marshall Alan-Brooke) was firmly against this owing to many reasons: lack of experience vis a vis highly seasoned German troops; lack of air superiority (air superiority vis a vis amphib invasions was just starting to be understood); lack of enough landing craft, and expected heavy casualties on the part of Britain. Nearly every historian I've read seems to agree on this.

The brits favored a more indirect approach by a joint Brit/American landing in North Africa which would help relieve pressure on Gen Montgomery who had retreated to Egypt fighting Rommel's Afrika Corps. the US joint chiefs did not agree with this, partly they saw it as pursuing a Brit strategy of not fighting Hitler directly while protecting their own colonial interests. Gen Marshall, representing the US army, favored an offensive in the Pacific if they could not invade France.

Ultimately the decision was made US president Roosevelt, who overruled the joint chiefs and decided to go with the British plan. I am not sure if he ever gave his reasons but obviously, Britain was one ally he needed to keep on his side; I think politically he had intuition that supporting Churchill and Britain would be mutually beneficial. Also, I think he understood that american forces really needed to start fighting in large scale if they were to become as skilled as the Germans. Fighting in Pacific with its long distances and small islands would take a long time to get everyone into combat experience mode.

Apparently, the Torch landings caught the Germans almost entirely off guard. Part of this was that they were focused on the battle at Stalingrad and also the forces under Rommel were in retreat from El Alamein. They also seemed to have little unified control at the top; it was mostly Hitler getting ideas and then insisting on them w/o understanding the realities. Hitler often had good intution (e.g. invading Norway when his commanders said it couldnt be done) but obviougsly a lot of operations require detailed planning, contingency plans, etc. Apparently no one thought about the possibility of landings in North africa, the Italian intelligence saw the build up the germans assumed it was another convoy to Malta. And no one really studied the ramifications of all that.

As it turned out, the landings took place a few weeks after the germans retreated from El ALamein so the timing was good. Obviously the americans were totally inexperienced so a lot of mistakes were made. However, the loss of life was relatively cheap. THe French who were there surrendered after a couple of days because their leaders like Admiral Darlan thought it better to dump the Germans and look to the US/Britain for the future.

An american direct assault on france was almost certainly out of the question in 1942. Many reasons, one them being lack of shipping, including landing craft which were in the very early stages. Also it would take much time for a build up of supplies and men in Britain. ALso the british high command was not willing to take on heavy casaulties.

Also, the US troops were totally green and there would be great waste of lives if they fought the best German troops. German troops in France could be quickly reinforced by rail while the allied invasion would have to rely on ships landing on beaches or harbors. It took two years to develop these methods before D Day, and a lot of lessons. to try it in 1942 would be folly; it would be the one good way for the allies to toss away all their advantages by making a risky attack, with large forces against highly skilled german troops at their peak. The allies had the advantage of time, making a huge risky attack early on would have probably been a mistake.

By 1943 the US high command was indeed willing to make a cross channel invasion though Brits were still against it. There was issues of having suitable air cover, as this was starting to be understood as crucial to any major amphib invasion. Again, lack of landing craft was still acute problem, much of it tied up in mediterranean effort in Sicily.

So an early effort at a cross channel attack was possible as early as 1943, but certainly not in 1942. They didnt have enuf of a build up in the UK. THe troops that landed at Casablanca came directly by ship from the US mainland (the other two landings left Britain), so that might give an idea that the jump off pts were not like they were in 1944.