Post surgery he will be very weak. You may want to consider not using stairs for the first one or two weeks. People have done it and it takes alot out of them to do so. Generally post surgery, your very weak, take frequent small naps, try to do as much walking as possible, taste is all messed up so he probably won't want to eat very much, He may have difficulty sleeping. Seems we sleep for one or two hours then were up for that or more. In general is whole body will be going through a reset phase. It's best to get a recliner on the first floor and make a bed out of it with lots of pillows. Only he'll be able to determine what he can and can't stand to sleep on.
The anxiety is normal, but don't let it rule you. What is about to happen is going to secure a future for the both of you. Without it, there is not much of a future left, it's that serious. Your probably worrying more about it then he is. Rest assured, he's scared too! If he's not, I'm wondering about him.
I've stressed over and over again that Coumadin is not the evil that the medical community paints it as. It really isn't that big of a deal. If he were to get cut, he'll bleed a little longer, but that's about it. The bleeding is treated the same as with any other, direct pressure until it stops. The down side is the frequent testing involved. If you read the Roundtable Symposium that bvdr posted, he'll likely be on Coumadin anyway at some point down the road.
I just want you to gain as much "Good experienced" advice from those that live this life, not the hearsay of those who do not.