无连词让步状语从句

Were the danger even greater, I should feel compelled to go.

书上说，从副词even可以看出来，这是一个无连词让步状语从句=Though the danger were even greater。

我的迷惑是：

1）为何说从副词even就能看出来， 怎么样理解？

2）让步状语从句一般使用目前虚拟式, 而这里为何是were式虚拟？ 能否从“句意”来剖析或理解？

3）句中，主句虚拟I should是不是是英式英语？ 若是美式英语，是不是使用I would呢？

这个句子省略的连词不是though，而是if。

If the danger were even greater, I should feel compelled to go.

= Even if the danger were greater, I would feel compelled to go.

Even if 引导让步状语从句，带有假设条件意味。可能是真实条件，也会是虚拟条件。所以主从句可以用陈述语气，也可以用were式虚拟语气。