Would you be okay with eating halal meat that is not labeled?

Only packaged meat is labeled. If you buy meat in a real butcher, be it Kosher or Halal, it is not labeled. You just have to trust in your butcher. If you eat in a Kosher or Halal restaurant, the food you are served is not labeled either. So my answer to your question would be Yes, but I would not purchase packaged meat that was not labeled.

I would be more comfortable with unlabeled Kosher meats. There are Kosher butchers in the US whose standards so far exceed government standards that they are exempt from inspection. The same cannot be said for Halal butchers in this country. If it's purity and cleanliness you're after I'd suggest Kosher meats for greater surety.

As I am not Muslim I don't go to Halal butchers. But if a Muslim friend or neighbour invited me to a meal I would be happy to eat it, same applies to Jewish/Kosher.

If it's not labeled, how would I know it was halal? So, yes, I guess I'd be OK with it.

Yes. Just as I would be fine eating Kosher food.

yes.