Yes. We say すみません when we bump into somebody. It implies an apology in this situation. You can replace it with 'sorry'. As you said, we also use すみません before you want to ask a question to somebody. In this case, it can be an useful word to start a conversation with somebody who you don't know or who are superior to you such as your boss or older people. It implies 'sorry for interrupting you.', 'can I talk to you?', ' can I ask you a question?' and so on. You can replace it with 'Excuse me' as well. It's a polite word, so I wouldn't say すみません to my family, friends or somebody who are close to me. hope it makes your understanding more clear.

You are right.正しいです。