Is there a way to upload photos to WordPress via FTP instead of uploading them one by one through the dashboard?
Also, does WordPress’ built in gallery allow commenting on each individual photo? If not, are there any simple gallery plugins out there that has this feature built-in?
Another option (one that I’m using to convert from NextGen Gallery to native WordPress galleries), is to use the Add From Server Plugin, to import images to the WordPress Media Manager.
Nextgen-gallery has all those features you needed, but not a simple plugin.