Mine was also stuck at the back with a bit of tape (for grounding?) I did my best to make sure it was replaced during re-assembly.

Agree. Same as my laptop.

Yes, it was taped on their quite strongly. I just tried to make sure the tape stayed stuck to the speakers and not the battery.

The replacement battery I received from ifixit had longer wires than the original battery which made re-installing it a bit awkward, but I was able to bend them to the side a bit.

Mine was missing the lower left and lower right screws.

I skipped this step and was able to gently pull it out when I removed the battery in step 8.