As to stopping A-bombs with Me-262's, good luck with that. The Me-262 was potentially a decent enough plane, but it wasn't a magic bullet. If the Allies sent over several hundred B-29s (which they would undoubtedly have in the European theatre by late 1945) escorted by late-model P51s, and one of those B29s had an A-bomb, chances are very good (80-90%) that the one with the A-bomb could get through.
Me-262s might be capable of inflicting unsustainable losses on Allied bombers by attrition over a period of time, but nothing I've seen in the literature even remotely claims that they would have been able to wipe out a group of several hundred or even a thousand Allied bombers, even unescorted one. Granted, escorting P51s wouldn't be as fast as an ME-262 in level flight, but with an altitude advantage they were quite capable of building up enough speed in a dive to more than match an ME-262. Given enough P51s, and in all likelihood better pilots, a mass P51 versus ME-262 battle would see a lot of losses on both sides, losses that the Allies could make up quicker than the Germans, both in terms of planes and in terms of trained pilots.
Another aspect of the ME-262 question is that the plane was rushed into service. Engines were initially very unreliable, averaging maybe 10 hours before failure. That improved somewhat, but even postwar the Allies quickly discovered that flying Me262s around wasn't something you wanted to do unless you had to due to unreliable engines.
The US didn't rush their P80 jet fighters into production because they didn't have to, especially after the war in the Pacific ended, but they had a dozen or so available for service trials by October 1944, and the P80 was still in mass production by December 1945. The P80 might not have been quite as hot of an airplane as an ME-262, but it was reliable and the US planned to build a ton of them (5000) if the war lasted long enough. The US used the preproduction models to train pilots on how to fight jets. I'm guessing that the P80 would have probably been in mass production by October 1945 if the war hadn't ended--probably sooner if the Germans had suddenly been able to swat Allied planes out of the skies at will with the Me-262.
All of this is not to say that the Germans couldn't have survived into 1946. If they did though, one of three things would have had to happen: (1) the US would have had to run into a glitch in developing A-bombs, or (2) have decided not to use them for some reason, maybe to protect the secret of them, or possibly in order to build up a big enough stockpile to launch a truly devastating attack, or (3) THe Germans might have called the US bluff in the aftermath of an atomic attack, and an atomic attack in 1945 would have been a bluff of sorts because while the few we had were devastating, we didn't have many, and it would have been months before we got more.