Lots of questions re setup

Lots of questions re setup

Hi re inventory cannot find the info online.
Looking at the way books is set out  I see info in inventory that is not in books, for example SKU, is inventory designed to suppliment or replace invoicing in Books.
Also need info re setup in inventory in regards to NEW ITEM GROUP, as currency can be set here does that mean I  can set a group say for example my Belgian suppliers Euro Tax rate 21%, Italy another group tax rate 22% and so on.

I understand that the price of inventory is included in books, I can mange well just using books if inventory is extra.

Also import products, manual, I expected a sync.
Once inventory is setup does it sync with items in books?