Looking to buy a Synology DS1812+ and have some questions

I am looking to purchase an NAS solution to back up my data. I am looking at the Synology DS1812+ with 8x4TB drives in it.

I currently have 14 USB 2.0 & 3.0 External HD 2TB to 4TB in size equaling 42TB total size. I want to back up the data on these drives to a Network attached device. I am looking for some guidance as to what configuration would be practical and most desirable. Specifically I am not interested in going with a RAID configuration since this is a backup and I already have another copy of the data that will be stored on this device. I have done some reading on the subject and if I understand correctly JBOD would not be a very good solution since I understand that if one drive dies I will lose the data on all drives since they are connected together. Am I understanding this correctly?

If this is indeed the case and since a RAID configuration doesn't help me what type of setup would you suggest and is an NAS device even going to be able to do what I want it to do which is just be a destination to back my data up to?

Another consideration for me is since I have so many drives and that doesn't even include network drives that are taking up drive letters I only have a few drive letters available for me to use. How do drives in an Network attached device show up in Windows?

Thanks for any help anyone can provide