is ok to backup phone to icloud instead of hard drive

Apple has preferred backups to iCloud to iTunes backups (on your computer's hard drive) since iCloud was created. It's incredibly easy to turn on iCloud backups, as long as your iCloud account has enough space for the backup. To turn on iCloud backups on your iPhone/iPad, open Settings. Go to the top and tap your name (subtitled "Apple ID, iCloud, iTunes & App Store"). Tap on your device (subtitled something useful, like "This iPhone"). Tap iCloud Backup. Then tap "Back Up Now" on the same screen. Apple has a guide. iMore has a guide.

Yes. In fact you can do that automatically daily when it is locked and connected to a WiFi network. I do a backup daily like that.