Well, his behavior is abnormal, and your setup looks and sounds good, so I would recommend a parasite check. Given his feeding history, this is a good thing to rule out, because a parasite infestation can cause loss of appetite and irregular feeding and fasting.

At age 1, he should still be eating weekly, unless he's actually breeding during the winter. Even then, he should be eating weekly the rest of the year.

Do NOT feed him in a separate cage. This causes stress, and he's quite unlikely to feed if he doesn't feel secure.
Don't leave the rat in his cage for longer than 15 minutes. If he turns away from it and starts roaming, remove it--that means he's not going to eat it. The longer you leave it, the more it will stress him, after that point.
There's definitely no reason to leave a rat in long enough for it to start chewing wires.