The only comment I'd offer is to ensure you retain a windows laptop going forward. We are an apple house but I still on occasion have to fire up the windows machine for compatibility with old files, hardware and applications.
Use the opportunity to throw a fresh lightweight install of the OS on the windows machine(s) and they'll be perfectly serviceable.
The rest of the plan seems reasonable, but macs are also prone to bloat as more applications and data are thrown at them so try to limit the kid's installs :)