1) There is nothing wrong with minor movements.Also no need to repeat any zikr.
2) Concentrate in Namaz which need practice. You can’t get it at sudden but yes you could do that by keeping it in your practice.
3) If you have spoken something in Namaz knowingly and it has meaning then do Sajdah Sahve.
4) You are allowed to say Alhamdolillah but normally we dont say when we pray furada.