"Why is it so noisy here?"
Translation:Почему здесь так шумно?
Loud and noisy are not exactly the same thing. Beautiful music can be loud without being noisy, and an environment could conceivably be thought of as being noisy if the noise was very annoying, even if the actual decibel level was low.
Loud and noisy have similar but slightly different meanings in English. For example...Loud music pertains to the VOLUME of the music being played. Noisy music pertains to the QUALITY of the music being played. Another example...A loud voice can be heard better than a soft voice, whereas a noisy voice can be distinguished or recognized from a monotone voice.
I'd like to know this too. In other discussions it was always said that тут and здесь are interchangeable.
It's not about the choice between "здесь" and "тут", but rather the word order doesn't sound natural. We don't usually put "здесь/тут" in the end of the sentence. It's possible, as it doesn't change the meaning of the sentence, but it sounds weird.
Is "так" not conjugated (-ая, -ой, etc.) because it's not describing an actual object in the sentence? Basically, there's no reference to how it should be conjugated, so it isn't? Just trying to clarify when to use just "так" and when to use the conjugated versions.
так is adverb in this sentence and means 'so', can't be inflected.
такой and такая (and такое for neutral) are adjectival pronouns and they are usually mean: as, similar, like. Example: he is like everybody - он такой как все. Sometimes they can be used as a sort of amplification of the quality similarly to English 'so' (might be confusing with the first one). Examples: she is so smart - она такая умная. the car is so expensive - эта машина такая дорогая (there are no articles in Russian, so for the definitive article you may use этот (m), эта (f), это (n))