I totally agree about booking flights separately. I use www.skyscanner.com
This is the link for USA Walt Disney World website https://disneyworld.disney.go.com/
I would just book the hotel with Disney.
Some things to consider for Walt Disney World
Most meals need to be booked in advance, unlike Disneyland Paris and California. Restaurant reservations are highly sought after, and the more popular restaurants reservations usually get booked up around the 100 day mark from arrival date
Almost all rides and attractions are on the Fastpass system. This is an electronic system linked to individual wristbands called Magic Bands. Just like the restaurant reservations, the electronic Fastpass need to be booked in advance around the 100 day mark from arrival date