状语从句做插入

On opening the door, she perceived her sister and Bingley standing together over the hearth, as if engaged in earnest conversation; and had this led to no suspicion, the faces of both, as they hastily turned round and moved away from each other, would have told it all.

她一打开门，便看见姐姐和Bingly 一起站在壁炉前，好像在热切的交流着，如果说这个情景还没有什么好疑心的，那么他们匆忙转身彼此躲开的时候，两个人的脸就全部泄露了真相。

1、stand over有监督的意思，在这表示站在……前面，怎么理解over表示"在……前面"这个意思？

2、and had...原句是if this had led to on suspicion吗?

3、as they hastily turned round...这里as相当于when吗？状语从句插在主句中很普遍，所以顺便问一下这是当插入语使用吗，和正常使用有什么区别？

请教各位老师！