Hello from JustAnswer.
We usually will allow a person that has undergone spine surgery to start walking when the patient has been discharged home, although they should avoid pushing, pulling, bending or twisting for a couple weeks. Since the doctor has instructed him to be on bedrest, then he must have had a more complicated surgery than average, but he will likely be able to start walking in a few days. Even once he is allowed to start walking, it is better to avoid sitting in one position for a long time
The wound should be kept clean and dry until he is told that he can shower or bath, which is usually after several days, so ice or cold compresses would usually be avoided.
From the perspective of diet, it is good to be eating a generally healthy diet, including a good amount of protein and fiber, but any foods that are high in protein and fiber would be good.
It is also important to avoid smoking, as this can impair healing from spine surgery. If he has never smoked, then this is not an issue, but if he usually smokes, it would be better if he can stop smoking while recovering from the surgery.
Is there any other information that would be helpful?