Why bad thing!!! It would be an awesome thing!
Depends on how far back into the past I go! It could be a matter of minutes or seconds, maybe even years. I'd be scared to see myself either way, to be quite honest! It may cause perplexity to my younger self and cause my younger self to be so dazzled that I never made the trip and thus... never knew that I would become perplexed in the first place!
If I were to travel into the past a few years, my younger self would age and become the older version of me that eventually goes back in time to meet myself who will then meet the younger version of me, etc... I love time travel. :P
No. There are two options that I can see here: either time works such that the future has already happened, or your interaction with your past self creates a new timeline/ dimension. In both situations it is fine to see your past self. If time works as the former (so that the past has already happened), then we can assume that whatever you do in the past will have already been taken into account, and so no matter what you do, nothing will change; the future will not be different. If time works in the latter way (so that your interaction with the past DOES change the future), then whatever happens because of your actions will not change you.
In other words, if you accidentally run over and kill the person who was supposed to save your life in the future, you will not cease to exist. Instead, you will have created a new timeline or dimension, and your past self will die before they can get to the same age as you are now, rather than be saved by the person you hit (unless, say, someone else saves them). However, you would be a part of a different timeline than the past self you are seeing, so you would still have been saved by that person you hit and can still be alive.
Or, another (potentially) harmless alternative, time could work in the same way as it does in Chris Heimerdinger's Tennis Shoes Adventure Series, so that when you go back in time, interact with your past self, and change the future, you just end up with memories from both timelines, so that both the unchanged past and the changed past are real and happened, only that the permanent results are those from the changed past. If that is the case, then, assuming that you interacted in some way with your past self and changed the past and therefore the future, you will simply have new memories along with your old ones, and time will go on so that your past self eventually ends up at your age too.
Actually.... I don't think that way would work. Too many things could happen, so dismiss that as an entertaining but illogical, complex idea and pay more attention to the first two theories. If for some reason time works in your scenario so that the Grandfather Paradox happens, then yeah, there could be a problem. But then again, it could be harmless. I personally think that, if traveling backwards in time Is possible, the rule would be that the future has already technically happened and your "changes" have already been taken into account. Most likely, it wouldn't be an issue.
Of course not. I'd give myself a big hug and would give every single information that would help Me in the past to become a better person in the future.