What dstinations Backup Mannager can use?
Currently Backup Manager can store backup on local system and remote server using rsync tool.

Dose the Backup Manager support incremental backup?
Yes, Backup Manager stores all files in incremental style. It saves last full backup + all changes made last N days.

How many days can Backup Manager can store?
You can configre how many days you need to keep backups on Backup Manager plugin settings page.

I have delete one file on my site. Do I need to restore full backup to get this file?
No. You can restore only one file or folder. Aslo you can save any file or folder into GZIPPed tar and download it.