1. Claw is indeed a better option but last edition they were both good in different situations and the Nob benefited from having both weapons available. As always I advise magnetizing this arm, in case rules change again.
2. Read into it, what's your impression? I think it's pretty unambiguous ("you can do each once").
3. Second option. Equipment this edition has quantum properities - it is exactly where you want to use it