If you say "sushi wo taberu no?" then, this means "Do you eat sushi?'' And if you don't, just "sushi wo taberu no" means "I eat sushi'' But by putting "no,'' it means that you enphasize " to eat'' "sushi wo taberu koto" means "to eat shushi." So it's not the complete sentence. You can use like this: "sushi wo taberu koto wa tanoshii desu" ( It's enjoyable to eat sushi.) I hope this would help...

Both 'verb(dictionary form) + no' and 'verb(dictionary form) + koto' are used when you nominalize verb. 'sushi o taberu no wa suki desu' - 'i like eating sushi' 'sushi o taberu koto ga deki masu' - 'i can eat sushi'

the predicate decides which one you should use.