audit u/s 44ad

Yes, as per combined reading of Section 44AD(4) & 44AD(5) (subject to total income exceeds the maximum amount which is not chargeable to income-tax)

1. Yes, according to sec 44AD(4) any eligible assessee who is has availed the benefit of presumptive taxation will need to follow the same for 5 consecutive AY. 
2. In your case, you need to compute profit as per sec 44AD for 5 consecutive AY (2019-20 to AY 2023-24) 
Please correct me if the above solution has an alternative view.