The Future Lies in the Past, part four: Not Changing the Outcome, Only Causing It

This will address question #7 in great detail.

Here's an excerpt from the MuggleNet/Leaky Cauldron interview with JKR:
MA: Was there anyone else present in Godric's Hollow the night Harry's parents were killed?
JKR: No comment.
[All laugh.]
JKR: I'm sorry!
Okay, so I think the real answer is "yes"....

Now, I've recently extended my theory to include the events in the cave when the real locket horcrux was stolen. However, I gave question #7 answers to that bit in a previous post. So, here I'm focusing on the things that Harry might have done during and after Voldemort's attack on the Potters....

This will require re-reading all six books, so bear with me. I'll make changes to this post as I find good evidence to support my theory, so look here for updates.

Just for reference, here's my original question #7:

7] How will his actions affect the outcome while he's "living in the past"? What bits of canon can give us clues that he is there, not changing things (since PoA showed us that can't happen) but making things happen as they do?

PS/SS gives these clues:
I'm still re-reading this book right now, looking for canon to support my theory...so check back later! :)