Exactly. すき is an adjective. Think of it as "enjoyable". Then, there is a structure that goes: ··· は ···　が adjective　です。Talking about (は), something (が) is (adjective). For example: 私は髪が長い。Watashi wa kami ga nagai. Talking about me, the hair is long (I have long hair). 私はつりが好きです。Watashi wa tsuri ga suki desu. Talking about me, fishing is enjoyable (I like fishing). 私は新しいコンピュータが欲しいです。　Watashi wa atarashii konpyuuta ga hoshii desu. Talking about me, a new computer is desirable (I want a new computer). Hope it helps. Cheers.

Ga isn't used for watashi in this sentence, ga is for the thing you like. when you omit watashi, you omit wa. And when you omit the thing which you like, you omit ga. You put です after すき, because すき is an adjective not a verb.

"Ga" has many uses that I will not go into here. What I will say is, "ga" is a Topic (T) marker whereas "ha" tends to be a Subject (S) marker. So, S は T がすきです。= Subject likes Topic. Consider attaching the particle to the preceding word in your mind. Remember particles like は or が indicate the relationship of words in a sentence