Min Nan expressions: spelling, meaning and pronunciation?
This site will be the reference for the whole answer.


That site suggests 格微微 | keh-bui-bui: seems I guessed the "bui" correctly. Maybe the "keh" is some kind of suffix to "bak-tshiu"? Actually, that site seems to suggest writing "keh" as 激, glossed as 裝作, "pretend". Given the gloss, I suggest 假 would be better, so "假微微 | ké bui-bui". The site glosses the whole sentence as 因為自己癡心貪愛，眼睛只微微張開，沒有認出情郎的真面目, or "Because of one's infatuation and passionate love, only open one's eyes a little, and not recognize the loved one's true colors".
That site just gave me what is probably the correct character for "lam": 湳 | làm… but "mud"? What would "mud" be doing here? Maybe this is in fact not the right character… Well it glosses the expression as 涕泗橫流, "to weep uncontrollably". Maybe I should spell it 泗湳垂 | sì-làm suî, literally "mucus-mud drip". Tone of "sì" uncertain, copied that of 四. Yep, that's the characters the site suggests.
Too bad the site doesn't have that part…
三聲無奈哭悲哀：「三聲無奈」，再三喊無可奈何，這種時候，我是不會只喊三聲。 I don't get this. Does 三聲 mean 再三 or 喊三聲? According to this, it 旧指军中用以传令的金鼓、笳、铎之声 (used to indicate the sounds of the gold drum, whistle, and bell used in the army to transmit orders". I suppose that, if all three sounded, the order was "complete" (cfr. 三声既全, with the three sounds it's already complete), so in the song it might mean "completely". Asked a follow-up.
「專望」為「特別期望」, so 專望 means 特別期望, i.e. "especially hope". So I was about right there.
The site glosses the whole sentence as 一心想嫁給情郎，如同花朵只仰望你來採, but doesn't gloss tshái separately. That big gloss means "wholeheartedly wishes to marry her loved one, like a flower just looking up to you so you pluck it". So tshái is literally "pluck", and the flower to pluck is the singer. So the whole sentence should translate roughly to "[I] have blossomed, and hope you will pluck [me]".


Also, the metaphor of her being compared to a flower is in the last line too: "A beautiful flower has become a pining plant", meaning she, the beautiful blossoming flower of verse 2, has turned to a sad plant full of lovesickness.