Thanks for your comment and feedback about Synology products, and welcome to the community.
About your questions
1. The risk of removing the USB HDD from the Synology system without ejecting it is the same risk as removing USB HDD from your Windows/Mac computer without ejecting it. You have a small risk of data loss because some of the data is stuck in the RAM or Cache of the HDD - properly ejecting the drive will flush this data to the HDD. As such, it's recommended to eject the drive from the WebGUI to ensure that all data has been flushed from the system.
1. You could conduct port forwarding of the Synology system, and therefore manage the system remotely from any Web-capable computer
2. No, the Synology system will not eject the USB/eSATA drive after conducting a backup, as the USB/eSATA drive can be used for other storage purposes (after 722 and above)
2a. In theory, you could create your own Linux Script to eject the drive on a certain time period, however you will have to consult with The Underground
for further information. However, the problem with this is that if a backup is taking longer than usual, and the drive is ejected, the backup will fail
3. You could use Network Backup with a DS108j located off site - and data from the DS207+ can be sent through the internet to the DS108j for backup purposes. In firmware 803 and above, you can even enable the incremental option, where data deleted on the source will not be deleted at the destination.
Hope this clarifies things for you, have a good day.