Is it better to use wine, grape juice, or beer for havdalah during the nine days?
Wine or grape juice. Beer should not be used.
Is this specific for the nine days, or is it better not to use beer for Havdala the whole year?
Beer should not be used all year either.
For havdalah this week it’s best to use grape juice and not wine.
Thanks. May I ask why beer should not be used?
What is the reason why beer cannot be used? Is chamar medinah not a valid argument?
Since these days it very easy to obtain wine or grape juice (i.e. take a quick drive to the nearest supermarket and buy), there’s no reason to rely on the heter of Chamar Medina. If in fact one find themselves in a situation where there is no way to obtain grape juice or wine he may use beer as we do consider it Chamar Medina.
If you are at the home of someone who makes kiddush shabbat day or havdalah with chamar medinah but there is wine at the table, are you yotzei with their brachot or should you make your own kiddush/havdalah?
That is an excellent question.
On the one hand you are incumbent to follow the Baal Habyis, on the other hand you should definitely make kiddush shabbos morning on wine/grape juice.
Many hosts will ask you if you prefer to make your own kiddush, and if asked you may surely do so. if not, there is no question though that kiddush on schapps would certainly not permit drinking wine, so I would recommend without fanfare or making an issue you just make a borei pri haggefen and drink wine. All the other verbiage we add to kiddush shabbos morning while beautiful is not necessary for kiddush.
As for Havdalah, I would say make your own later at home.