20 June 2014
it is include in your current year salary filing the return. you can claim rebate u/s 89, if your arrear is related to many year then you can take help of any tax consultant for taking this relief.
20 June 2014
the calculation will be done in the same manner as provided in the calculator. you can find tax rates for earlier years on income-tax department website.
yes, net tax liability is to be paid only after adjustment of section 89 relief.