Commas, dashes, and semicolons

After a while he had already moved so far across that it would have been hard for him to keep his balance if he rocked too hard. The time was now ten past seven and he would have to make a final decision very soon. Then there was a ring at the door of the flat. "That'll be someone from work", he said to himself, and froze very still, although his little legs only became all the more lively as they danced around. For a moment everything remained quiet. "They're not opening the door", Gregor said to himself, caught in some nonsensical hope. But then of course, the maid's firm steps went to the door as ever and opened it. Gregor only needed to hear the visitor's first words of greeting and he knew who it was - the chief clerk himself. Why did Gregor have to be the only one condemned to work for a company where they immediately became highly suspicious at the slightest shortcoming? Were all employees, every one of them, louts, was there not one of them who was faithful and devoted who would go so mad with pangs of conscience that he couldn't get out of bed if he didn't spend at least a couple of hours in the morning on company business? Was it really not enough to let one of the trainees make enquiries - assuming enquiries were even necessary - did the chief clerk have to come himself, and did they have to show the whole, innocent family that this was so suspicious that only the chief clerk could be trusted to have the wisdom to investigate it? And more because these thoughts had made him upset than through any proper decision, he swang himself with all his force out of the bed. There was a loud thump, but it wasn't really a loud noise. His fall was softened a little by the carpet, and Gregor's back was also more elastic than he had thought, which made the sound muffled and not too noticeable. He had not held his head carefully enough, though, and hit it as he fell; annoyed and in pain, he turned it and rubbed it against the carpet.