What's the difference between 我住在 and 還活著? I think both 我住在 and 還活著 have quite the same meaning (I'm alive), can I use evenly one of them as I like or are there some rules that force me to distinguish their use according to different contexts?
They are two different things;

我住在 = "I live in/ at" - e.g.  我住在香港 (I live in Hong Kong)

還活著 = "still alive" - e.g. 我還活著 (I am still alive)