RE: Need tables names for the invoice, salesOrder, creditmemo, Inventory etc.
Your list is displayed in a weird way. Could you fix it, please?
By the way, finding many of them should be rather easy. For example, do you know that you can find object names directly from AX GUI?
Nevertheless some make little sense. For example, "Inventory" is a whole part of the application, not a single table. You should specify what exact information you're looking for. You can also find out that looking at certain data directly in database is pretty complicated. For example, if you want to see get the available quantity of an item, regardless of inventory dimensions, you'll have to calculate it by yourself. Also, don't forget to take into account DataAreaId and Partition.
What exactly are you trying to achieve and why do you believe that bypassing AX business logic (and security, caching etc.) will be better?