Ok, let's not turn this into another LL thread, but you're also wrong on every count.
1. The first LL delivery to the USSR left in June 1941 and arrived in September. It carried 40 Hurricanes, 550 mechanics, and pilots to train Soviet pilots. For the US, "pre lend-lease" was signed in June 1941, and the first protocol period was in October 1941. The Soviets certainly did not have the upper hand then, and 1941-1942 lend-lease was critical, particularly in the Caucasus front, keeping the supply line to Leningrad alive, defending the skies above Moscow, and getting Soviet industry not only back on its feet, but more productive than it had been previously with new, better machine tools, raw materials, and literal factories that were taken apart and shipped to the USSR. Without those Soviet industry would have likely taken until the end of 1943 to recover fully (instead of the historical late 1942) and even then it would be less formidable with shortages of machine tools, inferior machine tools where they did exist, and a lack of raw materials.
2.
No it didn't.
In fact, a large part of the success of Operation Uranus (which really tuned things around for the Soviets) was that AGS had its mobile reserves redeployed in anticipation of Husky, so once the Soviets broke through there was nothing to stop them.
3. If they did, they would have fewer planes, tanks, guns, ammunition, etc. Nothing exists in a vacuum, and in the USSR's case they simply didn't have enough manpower and factories to go around. If LL stops, the Soviets have to produce more planes, tanks, millions of pairs of boots, a huge amount of their communication equipment, field ambulances, trucks, locomotives, machine tools, petroleum products, food, and explosives (lots and lots of explosives) themselves. They would need more factories and more people in the factories than they had historically to do this. Any factory producing things they historically received through LL is one factory fewer producing T-34s. Every additional factory worker they need is one fewer on the frontlines.
4. Based on what metric? Soviet production numbers are incredibly skewed compared to other nations (damaged and repaired tanks are counted as produced, no matter how minor the damage), so that's out. GDP? That's an incredibly sketchy way to measure the overall wealth of a nation in any circumstance, but especially in terms of wartime production, where markets don't work like normal, and even more so in the USSR which was notorious for skewing production numbers and GDP, among other statistics. The only thing GDP is good for is measuring growth. So that doesn't work either.
I should point out that I'm in no way discounting the Soviet contributions to the war, but the belief that LL was useless or was insignificant at any point after the Fall of 1941 is simply false.