1 &2 are both correct. 2 is more accurate because in the Chinese sentence 啤酒 is the subject. A simplier way of emphasing the fact that there is no beer is "啤酒没了。” or “没啤酒了”。 If I want to say I am done with the action of dring, I would normally say " 我喝完啤酒了。“ or even "我喝完了。“

Both are correct, based on the context. However, if you want to emphasize on "finish", use 光 instead of 完。 啤酒已经喝光了。Meaning beer has been finished up, no more left. The same rule, 吃光 (to eat up)，用光 (to spend up)，卖光 (sold out), etc.

In contexts as follows, the meaning focus is bouth on 完. 1) Do we have any/some beer remainifg for the coming guests? 2) Have you finished your beer?

Normally, the emphasis lies with the beer. You can only "drink" beer (You can't eat it, right?). Unless you deliberately put very heavy tone on "喝", then it shall sound like that you are emphasizing "to drink", which in another way implies that there must be another way to consume the beer (by pouring it into sink, perhaps?)...

The emphasis is on the act of drinking.