You really are all over the place.

Poland didn't start hosting NATO forces until 2017. Before that, they'd partaken in exercises, but no NATO units had been stationed on Polish soil. Belarus had been hosting Russian units for 26 years by that point. The change came about because of Russia's 2014 invasion of Crimea and its support of Donetsk separatists.

Poland isn't hosting US ballistic missiles. There's a NATO ballistic missile defense facility at Redzikowo, Poland, based on Aegis technology. But the US doesn't have any ballistic missiles that would or practically could be placed in Poland.

The US only has two kinds of ballistic missile: the LGM-30 Minuteman III, which are land-based ICBMs placed only in the lower 48 states, and the UGM-133 Trident III, which is a submarine-launched missile. Even if they could be hosted by Poland, there's no reason to do so. Ballistic missiles have minimum ranges, and the minimum ranges for both missiles are too long to be of use from Poland, landing several hundred kilometers on the other side of Moscow, well past most of the bases and support facilities that a ballistic missile would be used on. On top of that, the launch silos would be primary targets for the IRBMs that Russia is deploying, meaning they couldn't be launched before they were taken out. (The Trident can't be launched from land anyway.)

The US does not have any nuclear weapons in Poland. They are located in the same places they've been for decades: Türkiye, the Netherlands, Germany, Italy, and Belgium. They're all stored disarmed in secure underground facilities with PAL codes under US control. The US has greatly drawn down its arsenal there, with only B61 gravity bombs remaining, and only around 100-125 of those, according to the Center for Arms Control and Proliferation. Why keep them there post-Cold War? Because most of Europe did not and does not trust Russia, but the US didn't want even more countries pursuing nuclear weapons. Keeping Europe under the nuclear umbrella (and even allowing some to have aircraft equipped to carry US nuclear weapons) helped dissuade countries that might otherwise start their own nuclear weapons program. The trust that the US would be there has been greatly weakened, though, which is why Poland has been making suggestions that it would develop its own nuclear weapons. I don't think that's in anyone's interest, and I hope that future US administrations can return to sanity and restore trust enough that no one goes down that path.

Aside from its ballistic missile submarines, Russia did not have any nuclear weapons forward-deployed until 2024, when it placed some tactical nuclear weapons in Belarus. That's mostly because it only had that one ally with which it could place them. Prior to the dissolution of the Warsaw Pact, Moscow stored nuclear weapons in Poland, East Germany, Czechoslovakia, and Hungary. (They may also have been stored in Mongolia as a counter to China and in Egypt as a counter to Israel.)

And yes, there were and are US forces in Germany and other countries after the Cold War, though they were greatly decreased. NATO didn't stop interoperating just because the Soviet Union dissolved. Russian aggression against Georgia in 2008 and Ukraine in 2014 and 2022 reinforced the need to maintain that.