Does it operate when IFS is down?
No wadaco/ScanIt is 100% online 

Does it support lot/batch number?  If so, is that configurable by product center or country/accounting entity?
It supports the lot/batch numbers that exist in IFS applications. I don't understand your follow up question, I’m not a functional expert.

Is a version available with IFS8?
Only as an extension to IFS Applications 8 as I remember it, so it have a smaller number of processes it supports (19), the new applications versions supports a lot more processes (60+). 

Does it require specific scanners or minimum technical specifications?
There is some minimum operating system requirements for the windows mobile and android app (if we are talking only about Apps8 now, later version like Apps10/Cloud support more different platforms/operating systems).
I can't find the exact requirements for Apps8 version but it should be similar as Apps9 version, but I'm not sure if these links are available from outside IFS
https://wit.ifsworld.com/Technology/prodcert/ProductCertification/SupportedPlatforms/9.htm
https://wit.ifsworld.com/Technology/prodcert/ProductCertification/SupportedPlatforms/WarehouseDataCollection.htm 

Does it require a specific barcode label printer or does it have minimum technical specifications associated with the barcode label printer?
Wadaco/ScanIt don’t care about the printer, but it is more of what kind of barcodes standards your device supports, plus the more advance ones like QR/GS1 might require later versions of wadaco like for Apps10