So, the reason why this is not being done is that by simply doing that I'd have no more access to the original /data.

1. If I copied all content to mmcblk1p2 (you're correct, that's it) and THEN mounted it on /data, in theory the system should keep working seamlessly. What if there are files in use when I copy/mount? No problem, right?

2. Will this be retained at reboot?

Thank you so much!