I'm not a native speaker, but have studied Russian for one year in university. It seems to me that находится just emphasizes formality or clarity of location--the difference between saying "My room is located to the left" and "My room is on the left." I could be wrong on this one.
To answer your first question, Russian has no present-tense form of the verb "to be." The only usage of the verb быть is in the past and future imperfect forms: for example, "I was eating", "I will be driving," "I was cold".
In Russian, if you want to say "I am hungry," you just say "Я голоден." But let's say you're a Russian speaker and you want to clarify you were hungry in the past--how do you differentiate the equivalent of "I hungry"? You invent a verb specifically for use in the past (or future) to denote the time of your hunger: Быть. For example: Я был голоден (I was hungry) or Я вуду голоден (I will be hungry).
I hope I answered your questions!
You can say so, but the meaning is slightly different.
1. You show a house to your guests for example and describe all the rooms there: "This is a living room, over there is a bathroom and to the left is my room." (Слева находится моя комната.)
2. You invited a friend to your house and you go straight to your room without a tour round your house. So you just say: "My room is to the left" (Моя комната находится слева)
Because it's not "on the left side", it's "on the left" or "to the left". Saying "on the left side" implies it's the left side of something. That "something" can usually be left out due to context. "On the left" is simply stating relative direction from the current location, not relative to a side of a thing.
Russian doesn't really have a single word corresponding to all meanings of "a chamber", so depending on context it can be "комната" too. For example "Harry Potter and the Chamber of Secrets" is known in Russian as "Гарри Поттер и Тайная Комната". But in general "a room" is a closer translation of "комната".
The English in that case is nonstandard in the sense that it employs ellipsis (skipping of words): one would be able to say "Situated to the left is my room", because it's syntactically complete. Omitting those two words, while understandable, does not possess complete syntax.