Rebate u/s 87a

what is the refund amount one will get is it Rs.2000(Tax - TDS ) or Rs.4000 (Tax - rebate -TDS )?

You have paid TDS of Rs. 14000 and your tax liability is Rs.12000 therefore your are entitled to get a refund of Rs.2000.
For the rebate of rs.2000,it has already been deducted from your taxable income thats why your TDS deducted was 14000 else it might have been 16000(The employer has considered the aforesaid provision).

Yes ,  you are awarded with the Relief u/s 87A. The reason is that for claiming relief under this section , you must have a tax liability and your Total Income must be Rs 5 Lacs or less. Your tax liability is calculates after considering this relief u/s 87A and from yhis net liability  , the TDS is adjusted to claim refund or to pay tax. 

Yes, Relief available.