Yes, now that you know about/remember the UGMA account, it needs to be reported on financial aid forms as a student asset.
You can’t move the funds into a parent or grandparent owned 529 because the funds aren’t owned by a parent or grandparent; they are owned by your child. What you could do to lessen the financial aid hit is to move the funds to a UGMA/custodial 529 account which would be legally owned by the child/student but would be reported on FAFSA as a parent asset, and might be considered a parent asset on CSS/Profile, depending on each Profile school’s own FA policy.
Yes, within the relevant IRS regulations and the 529 administrator’s program rules.
With different investment vehicles and different timing, it will be next to impossible to provide an equal amount to each child, but you can probably get close.
You should make any needed changes to FAFSA and Profile ASAP, but realize that these changes will probably delay accurate need-based FA offers from schools that are providing them. If making a school choice depends in part on FA offers, this might be a problem.