Logistics query

Dear All,

I have some queries.

a)  Unit Cost of an Item: = How it calculate and which table we get the value,

In mtl_material_transaction table show actual cost, prior cost, new_cost  . How we find the first cost of an Item when it enters in to the Inventory.Secondly is there any difference

between Actual cost and New_cost in mtl_material_transaction.

b) I have an single item (1 qty)in an inventory Org. I use Subinventory Trasnaction to move (2 qty ) which is negative it same Subinventory but different Location.

it shows -1 in locator 1.0.0 and  2 qty in on hand at locator a.0.0 but shows 1 qty on availibility window.