Sounds like more than one problem. A loose/worn/broken engine mount would certainly account for the knock on acceleration. The grinding could be due to other components perhaps touching (ie; exhaust), due to the engine moving. I doubt that it is the clutch release (also called thrust) bearing - the noise from them tends to be higher-pitched - more of a squeal, or rattle. If the clutch had a broken finger on the spring or the cover, you would certainly know about it and probably would not be able to engage a gear! Second problem sounds like a slight misfire - possibly a spark plug or lead breaking down, or perhaps an injector. Best bet would be to take it to a specialist - it may save you a lot of time!