BQ25620: several questions regarding Vin and OTG

Hi Team, 

There are several questions from my customer on BQ25620

1. Recommended Vin spec is up to 18V. last gen is BQ25601/D which is only 13.5V, what's the consideration to improve it? 

2. what's the consideration to improve OTG voltage to 9.6V?  also, why does OTG current go up to 3.2A, for which kind of load? 

3. it does not have IR compensation, right? 

4. why do we care about  efficiency down to 25-mA output current ? 25mA is quite low current in real application except for wearable EE. 

5. can Q4 (batfet) support soft-start?  

Thanks. 

BRs

Given