Hi Neil,
This likely is hormonal behavior. You can see if removing anything shiny or reflective will help. Because he is free flighted and not caged during the day, he will take that opportunity to exercise and maybe look for a mate Although for the most part, a male canary sings to attract a mate. But he may see his reflection and feels like he is showing off for a mate. As long as he isn’t hurting himself, I wouldn’t worry too much about him. If his flight seems frantic, it could be that something is scaring him. Since birds are prey animals, anything that approaches from behind or above or suddenly can cause a flight response. If he can see out of a window, he could get startled by wild birds, other pets, people or passing cars. Sounds from outside can also be scary.
As to his diet, have you tried him on a finch pellet? We do make a small granule for finches and some of the other softbills prefer this over the slightly larger pellet. Generally you can mix with their seed, and then gradually reduce the seed until he is eating the granules. However, some seed is still good for a canary to eat. If you can get him to eat pellets or granules, he will not need the added vitamins in the water. The fresh greens and broccoli also offer some great nutrition and are favorites of most softbills. As to picking at his feet, this is probably a form of grooming. I wouldn’t worry about it as long as his feet do not have any sores or growths on them. He also may be bored. Canaries enjoy the small, colorful plastic toys that are made for parakeets and small birds.
https://lafeber.com/pet-food/bird-species/finch/
Thank you for asking Lafeber,
Brenda