1) I'm living in Russia for already a few years.
Verbs can convey meaning about 'time', and a period of time; and other words in a sentence give us more specific information about 'time'. So, in your sentence:
I am living in Russia: this is Present Continuous tense.
Compare it with Present tense:
I live in Russia : this is a statement of fact. It is like a snapshot, an instant in time, 'at this very moment'. Other than that, it gives us no information about the past or the future.
I am living in Russia : this tells us that it is an ongoing activity over a period of time without being specific about ‘how long’. It implies that ‘living in Russia’ started some time in the past, whether it is your first day as a new citizen of Russia; you have been there a year or ten years; and that this will continue, whether for another day, year or till death. This is unspecified. It just tells us that this is an ongoing thing.
I might use this form if I was telling someone, “I am living in Russia at the moment, but next year I will be moving to Denmark.” My frame of reference is that ‘living in Russia’ is an ongoing activity for a while, and then a new ongoing activity will start, “I am moving to...”
So, Present Continous tense is not specific about time, the total length of this time. So, let’s add some of the extra words from your sentence:
“I am living in Russia for a few years.” Well, this now is more specific about the time period of this ongoing activity. Remember, it started some time in the past, continued to now, and will continue. So – some time in the past, you moved to Russia. You continued to live in Russia till this moment, and will continue to BUT intend to move. The total time of this period of activity in Russia will span ‘a few years’, from when you moved there in the past, till you leave some time in the future.
BUT THAT WAS NOT YOUR INTENDED MEANING.
‘a few years’ was meant to refer to the time in the past when you moved there, just up to this moment – nothing about the future! But that contravenes the sense, the meaning given by the tense of the verb.
To refer to a time period spanning the past, right up to this moment, we use another form of tense, the Present Perfect:
“I have been living in Russia for a few years.” : I moved to Russia some time ago, and as of this moment, the total length of time from the day I moved there, till now, is ‘a few years’.
So- Your sentence becomes:
“I have been living in Russia for a few years already, and…”
“I have already been living in Russia for a few years, so I am very familiar with…”
...which brings in a whole new ballgame, that of placement of adverbs!