Two Problems In order management (price list-Tax)

[Newman]

<font size="3"><font face="Arial">1-I Have Item his price in price list 100 and For Some Customers i Sell with prices 80 So i Do Modifier (Discount) :Application Method :New Price 80 So item price In Sales Order 80 Then i Do another Modifier (Discount on Line ) 10% And I Apply It on Sales Order Line But Application Apply Discount on item price that in Price List 100 Not That i Modify 80

And I Cant Change Item on Price List
will explain to you what i want
i have item (computer) his price in price list 100
i change this price in sales order to 80 by apply Modifier (Discount) :Application Method :New Price 80
And Then i apply another Modifier (Discount on Line ) 10% And I Apply It on Sales Order Line
but application Doesn't apply the second modifier(10%) on 80 no he do that on 100
i want the application to do 10%*80=8
he did 10%*100(the price in price list)=100
and i cant change item price in price list


2-I do Sales Order with 100 and i apply Tax On this Sales Order Then I Apply Charge (Transportation) But Tax Doesn't Apply on Charge (Transportation).</font id="Arial"></font id="size3">