1. All of it has same meaning as 'tool' but a little bit different. 도구 its meanig is tool. 연장's also. 공구 means tools for reparing something. But we usually use 연장, 공구 as tools for reparing especially. 2. We can just recognize 길 includes 도로. Theae have same meaning but 길's range of used is wider than 도로. ex) 도로에 차가 많다. 길에 사람이 많다. 내가 맞는 길(방법)을 선택한 것인지 모르겠다. 3. 욕실 is bathroom. 목욕탕 is for public bath. And 화장실 is washroom. (In any place can be used in this form)