Jeff, you are right, The instructions indicate a flat head screw driver. Since I ordered the kit with the part, it is easy to assume this will be part of it. My revised comment would be to highlight that the kit would not include it if pairing with the antenna cable replacement part order. Regarding the screw, big picture did not show the screw in orange, I mistook it as the one in later step. You are right it seems to be Phillips as shown in second small picture.

There is another guide that explains it, here is the link to it. iPhone Battery Adhesive Strips Replacement

IFIXIT should point in the right step to avoid issues on adhesive missteps.

Thanks to the guide and parts, I replaced my GPS antenna flat cable and battery. GPS at first does not seem to work yet. But once I Step outside and after quite a bit if time maybe 5 minutes, the signal caught up, it seemed to be fine. Even if it did not fix fully, it is way better than the complete loss of GPS.

No issues on Wifi and Bluetooth.

Yes, further, It never came out for me. But, I lifted slightly and that was enough for board to slide out. Did not want to force the palstic/rubber part to avoid breaking it.

I faced it today, You can use a 1.5mm flat head screw driver to remove it. The guide mentions this in step 36 for stand-off screw. Hope iFIX changes the guide to indicate the flat screw driver or remove the step here.