The guide has you remove the screws second because it makes it possible to remove the whole assembly without snapping any cables.

Did using the screwdriver damage the case in any way? I’d recommend being careful using a tool with smaller surface area as that will apply more pressure at the point of entry. As the guide states, a Jimmy may also be used instead of the spudger.

I’m pretty sure the seal is equally far away from the edge on all sides.

Did you use iFixit tools? I just checked and I believe Y00 is correct. Y0 slips too easily. My test was with the Y bits from the Pro Tech Toolkit.