Is it okay if I nullify all of my previous entries and just predict it the day or so before the match? I find I'm changing my mind a lot.

You can always change your prediction the day before, but I'm not going to nullify your previous entries because it's more work for me for no real reason. (Everything in this topic will get run through my script, and I would have to remove them manually). They'll become irrelevant once you do make your changes anyway.

I'm sorry if this has already been mentioned, but if I enter the team contest, will my individual results still be counted in the main contest, or do you have to enter one or the other?

I think you already saw the answer, but basically anyone who predicts matches is in the main contest. The team contest is something you can sign up for in addition.
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