Can I hold off until December to make a 529 withdrawal for all tuition paid year to date or do I need to take the withdrawals each semester?
Laptops seems to be debatable college expense but if the classes are online it should be a valid expense?
Yes, you can wait until the end of the year. The only requirement is that the withdrawal takes place in the same year as the expenses.
Laptop is a valid expense for a 529 withdrawal. It's debatable whether it's a valid expense for a tuition credit
Is there max cost for claiming the laptop?
No.