Is (theoretical) timetravel possible without automatically creating a paradox?

[RagnaToad]

EDIT: I deleted the original post, and decided to restart this thread with a more general and less hypothetical "let's-say-you-CAN" approach.

-What's your opinion on timetravel?
-Is it possible?
-What are the effects/dangers of altering the past? (e.g. the Butterfly effect)
-Would it be a good thing to be able to travel to (and thus see) "the future"? (If there is such a thing...)
-What would actually happen if a true paradox were created? (e.g. imploding universe theories)

Discuss topics like this thread's title and knock yourselves out