Re: Did First Contact change the timeline?
Didn't Picard state in "Q Who" that the Borg now know about the Federation because of the events of "Q Who"? It was never established that a transmission of any sort brought the Borg to the Alpha Quadrant, AFAIK.
For what it's worth, and OT from the First Contact time paradox, I always liekd the idea that by throwing the Enterprise into system J25 in Q Who, Q didn't tip off the Borg about the Federation's existence (after all, The Neural Zone implies the Borg were already scouting on the Romulan/Federation border), but he did let Starfleet know of the Borg's existence, giving them a year's worth of time to prepare for The Best of Both Worlds.
"Some days are better than others. They say that where I come from."
"Loudly, I imagine, on the day you left."
(Blake's 7 - Rumours of Death)