as a dog does 这里的does指的是pines away at the door of my hut 吗？

"I have sent a report from Grimpen to Princetown as to the death of Selden. I think I can promise that none of you will be troubled in the matter. And I have also communicated with my faithful Cartwright, who would certainly have pined away at the door of my hut, as a dog does at his master's grave, if I had not set his mind at rest about my safety."

老师：

1）who would certainly have pined away...这里是虚拟语气还是推测呢？我认为是虚拟语气。

2）as a dog does 这里的does指的是pines away at the door of my hut 吗？