Yes, multiple accounts for the same beneficiary can be consolidated (rolled over). The particulars will depend on the rules and procedures of the account administrators. Or, you can keep separate accounts and withdraw from any account whenever you want; they do not have to be drawn down one account at a time.
Distributions from 529 accounts can be sent to the account owner (the earnings portion of any non-qualified amount will be reported under the SSN of and taxable to the account owner), to the student/beneficiary or directly to the school (under these last two scenarios, the earnings portion of any non-qualified amount will be reported under the SSN of and taxable to the student/beneficiary). You or the student/beneficiary can pay qualified expenses with your own money and then be reimbursed by the 529, you can take a distribution from the 529 in anticipation of paying qualified expenses later, or you can have 529 funds sent directly to the school. Whatever works best for you and the student in terms of simplicity, convenience and financial considerations. Just keep good records, and you should pay qualified expenses and take 529 distributions for the corresponding expenses in the same year.
See Chapter 7 here for more information: 2023 Publication 970 (irs.gov)