If you have enabled the iCloud Photos Library on your iPhone, then are not all original images on your device. What you see in the iDevice Manager are thumbnails only, like on your iPhone. A transfer of images which are in the iCloud, is impossible. You have to disable the iCloud Photos Library in the iPhone settings.
The iDevice Manager marks photos and videos with different icons so that the type and nature of the photo can be recognized at first glance. This will save you time to recognize certain photos.
The transfer back from iCloud to your iPhone takes couple of hours, depend on the load (use / hibernation) on your iPhone and the WiFi and internet connection speed.
Starting with iDevice Manager version 10.12, the program also recognizes photos taken with other apps like ACDSee Pro or ProCam 8 and transferred to the iPhone photo app. ProCam 8 saves photo and video recordings automatically in the iPhone photo app. The saved HEIC or JPG photos ,also includes shooting in RAW or DNG file format. The ACDSee Pro app, on the other hand, saves the HEIC or JPG file by default. If you also want to load the Adobe DNG file later from the iPhone must activate the "Raw Capture Mode" in the ACDSee Pro settings.
Not every iPhone supports this function, even if the app can. The prerequisite is an iPhone X or later.
Yes, transferring the LIVE Photo Movie is possible with iDevice Manager 10.12 and later. The download of the LIVE video can be activated in the "Download" settings. This will not only download the JPG or HEIC photo from the iPhone, but also the associated *.MOV file.