Psychics: No. People have been scheming and manipulating others into believing something since the dawn of the modern age, often to extort money from them (or something else of value).
ET life: Yes. For years, science pitched the idea to the general public that life could only exist with oxygen due to it's usage as a fuel for cells. That theory falls apart immediately if you don't assume that all living cells in the universe require oxygen, and could instead sustain themselves on other elements. I don't know whether I believe in highly intelligent life out there (i.e. human-level), but I do consider that it's likely some lower intelligence life forms exist. Simple life forms akin to amoeba most certainly exist somewhere - I base this on the simple fact that such forms exist in the extremes of our planet.
Time travel: I don't believe time is anything but a manmade construct, but without it, we can't say when something happened or will happen. Light may travel at a constant speed, but I don't believe that it holds a specific 'link' to time travel. For example, I don't believe that if you were able to travel faster than the speed of light, that you would actually be able to experience the past, nor do I think you'd be able to catapult yourself into the future. What has happened has happened, and I believe that time travel would ultimately require more than just exceeding the speed of light (which seems to be the common theory).