Citi mention 4 Primermiles for PM and 4 air miles for Prestige, Hence confusion.
No one know for sure how things will be after merger. As per one person having good relationship with axis in my cards group, Axis will offer Reserve to Citi Prestige customers and Atlas to Premiermiles. Edge rewards on Reserve could be converted to edge miles. Axis will try his best to retain Citi customers and Citi have one of the highest per card spends. Take either PM or Prestige as long as you can get it, I don't see any harm
SC Ultimate is one of the good card have almost no exclusions for earning points however AFAIK SC Ultimate points can be transferred to BA avios only at very poor ratio.