도 is used before a noun, it means 'also', 'even' as you probably know. You can use it to just put emphasis on a noun or noun phrase. 걔 지금 어디 있는지 모르겠어요. I don't know where s/he is. 걔 지금 어디 있는지도 모르겠어요. I don't know even where s/he is. The second one emphasizes '지금 어디 있는지'. 그 영화 몰라요? Don't you know of the movie? 그 영화도 몰라요? Don't you know even the movie? A : 이거 어떻게 하는지 모르겠어요. I don't know how to do this. B : 저도 모르겠어요. I don't know either. In spoken Korean, 역시 means 'as expected'. I don't think I actually say any of those three examples CoreanBigSis mentioned above, I've seen them only in books. 역시 비빔밥이 최고예요. Bibimbap is the best as expected. 역시 넌 최고야. You're the best as expected.(talking to an extremely close friend) You could say just "역시" as its meaning is 'as expected'. A : 그레이 아나토미 DVD 빌려간 거 가져왔어? Did you bring Grey Anatomy DVD that you borrowed? B : 응, 여기. Yeah, here. A : 오, 역시. Oh, as expected.

well. You feel confused how to used these words differently? as you know, 역시, 또한, ~도 means like also, too, as well, either. but 역시 is adv, and ~도 is postpositional particle. so when 역시 is in the sentences, it will be like following: 나 역시 마찬가지다. I (feel, think, am) same, too. 네가 좋다면 나도 역시 좋다. I also like it if you like it. 그도 역시 공채를 통해 입사했다. He joint a company through open recuritment as well. and when ~도 is used in the sentences, it will be like below: 신화는 나이 삼십에 집도 있고 차도 있다. Sinhwa owns the house and car as well, even he is only 30 years old. 아기가 눈도 코도 다 예쁘다. This baby has very pretty eyes and also pretty nose. does it make sense to you now? hope it could be the help. :) have a great night. ps. about 저한테 도움이 되겠다니 기뻐요. 제게 도움을 주신다니 기뻐요. or 도움을 주셔서 너무 기쁘고 감사합니다. will be better expression. keep it going, you are doing very great job :)