1 I am tired of waiting for you to be finished. - There could be context you would say that, but probably what you mean is: "I am tired of waiting for you to finish your work." 2 As long as you feel pain, you are alive; and when you die, you go to hell to continue feeling pain. Is there any life without pain? 3 We would like to put (some of) our things in storage. How much will it cost (us)? 4 We still have twenty minutes left before takeoff. Let's dine somewhere. 5 In my opinion, there is no hell in the universe. Hell is only in our minds. - or: "Hell exists only in our minds."

1) Good! 2) Just some punctuation: You feel pain while you are alive, and when you die, you go to hell to continue feeling pain. Is there any life without pain? 3) In this context you "put" things into storage, or alternatively, you can use "store" as a verb and "store" the items. Also added a semicolon, because they're two complete sentences. We would like to put these things in storage; how much will it cost us? 4) "Minutes to spare" is an idiomatic phrase. Also added another semicolon. We still have 20 minutes to spare before take off; let's dine somewhere. 5) Just added punctuation. In my opinion, there is no hell in our universe; hell is only in our minds.