Rebate under Section 87A

Individuals having taxable income of up to Rs 5 lakh will be eligible for tax rebate under section 87A up to Rs 12,500, thereby making zero tax payable in the new tax regime.

Section 87A doesn't apply to new regime of tax slabs. 

Yes rebate is available even if you chose new tag regime. 

You can try to same using the tax calculator option also on income tax portal. 

Yes rebate u/s 87A is available up to income of Rs. 5,00,000 in new regime.