Bruce is a handsome fellow! Difficult to say anything about his weight from these (very good) photos, though. One would need to see him from above. As @Cbrugs says, the waistline should be visible right behind his ribcage.
The breed standard for English bulldogs is 25 kg so with that in mind...
Is it the cutting or just the fact that someone touches his feet that is the problem? If it is the cutting, perhaps a dremel would be better? And don't try to do all nails at once. I would try that at home before trying to lift him up in a sling at the vet if he gets agitated.
Good to hear your boy is ok, and hopefully you and your dad too. It is really scary to see your dog being attacked like that, but as others have said, report to the police and if the other dog's owner si to be found, make sure they (or their insurance company) pays for any costs you have.