I've had pretty good success with CleanRip https://wiibrew.org/wiki/CleanRip#Wii_DAT_download for acquiring ROM files. With it, I was able to backup my entire personal collection with minimal fuss, and can now enjoy that collection in HD with Dolphin's various enhancements.

For verification you generally want the Redump database, which has checksums for most disc-based console releases. Unfortunately they seem to be offline at the moment, or I'd share a canonical link. Look around for that.