"咖" here is pronounced as "kā", Duo pronounced the individual character as "gā" , which is wrong here. But in the word "curry", 咖喱(China)/咖哩(Taiwan), this is pronounced as "gā". These two words are almost all the usages of this character.
You have to add the character "了" if you want to put your sentence in the past. The character is added after the verb ("喝") to make it.
For example: "我们早上喝了咖啡."
You also can put a time word (character), like, "I drank a lot yesterday" to make it clear.
Absolutely agree! This syntax (an adverbial phrase) is perfectly acceptable in English. Perhaps not the most frequent, but acceptable. It helps me learn Chinese grammar if I know adverbs and adverbial phrases always go after the subject.