Is it permissible to wipe over socks when there are cracks on one of the feet covered with a bandage, and the socks are sometimes removed to clean the wounds and then put back on, and does the ruling apply to the healthy foot as well?

The person performing ablution (wudu') must wash the parts of the body involved in ablution, including the feet. If he is unable to wash them due to illness or a similar reason, he should wash what he can and wipe over the afflicted part. If direct wiping harms him, he should place a splint (jabeera) over it and wipe over the splint, while washing the healthy foot.