This depends on how large your photos are. The average size of photos from newer iPhones is between 5MB and 6MB. The 32GB Micro SD Card that is included with your Phone2Frame and Photo Backup Stick can store about 5,800 photos that are 5MB each.
Yes, the Photo Backup Stick keeps photos in their folders as they are on your computer. So, if you have organized your pictures into folders by date, location etc., it will keep this organization structure. You also have the option of not keeping your photos organized. If you choose this, all photos will be backed up into one folder on the stick based on the name of the computer.

The Photo Backup Stick will only backup photos once. If you do a backup and later do other backups, each new backup will only back up new photos so it won’t back up duplicate photos. 

If you have multiple copies of a photo (either in different locations or backed up from different devices), you can remove duplicates at the push of a button. Only exact duplicates are removed. Photos that are similar but not exact duplicates will not be removed.

By default, it will back up all JPEG/JPG photos because this is the most common format for photos. You can select to have it back up PNG, GIF, TIFF, RAW, BMP, PDF, EPS, 3FR, ARI, ARW, BAY, CRW, CR2, CR3, CAP, DATA, DCS, DCR, DNG, DRF, EIP, ERF, EFF, GPR, IIQ, K25, KDC, MDC, MEF, MOS, MRW, NEF, NRW, OBM, ORF, PEF, PTX PXN, R3D, RAF, RWL, RW2, RWZ, SR2, SRF, SRW, TIF, and X3F images as well.

For videos, it backs up M4V, MP4, MOV, AVI, 3GP, WEBM, MKV, TS, WMV, FLV, VOB, 3G2, and AVCHD formats.

The Photo Backup Stick Universal supports all iPhones, iPads, and iPod Touch (for iPads that have USB-C type data ports, backups must be done through a computer using the computer app). 

It also supports all Android devices that support OTG (devices without OTG support can be backed up using the Windows or Mac apps).

The Photo Backup Stick runs on Windows 7, 8, 10, or 11 as well as Mac OS 10.12 or newer. For direct backups on Android devices, the device must support OTG connections. For direct backups from Apple iOS devices, you must have the Photo Backup Stick Universal version. For iPads with USB-C connections, you must backup by connecting the iPad and stick to a computer.

The Photo Backup Stick Micro SD Card version plugs directly into computers, iPhones, iPads, iPod Touch, and Android phones or tablets. The Photo Backup Stick for computers plugs into your computer and backs up from phones and tablets that are also plugged into the computer.

The Photo Backup Stick Windows and Android apps support English, Spanish, French, German, and Japanese.