1. Android Pay = Google pay? No Citibank support. I have preference for Citibank cards.

Citi pay is a failed app.
2. Actually lastpass has the functionality (called auto-fill through overlay) and it used to be good before iOS 12 implement it. If you used both you will know why the latter is better.
3. I tried quite a few Apps, they work but do not approach the quality of ScannerPro. ScannerPro also comes with auto-upload to cloud functionality. To get this on CamScanner (Android), you need to to pay a $6 monthly subscription.
4. As for colors, I cycled through all the settings. It stills looks overly punchy. I used iPhone for work and Pixel for personal, so the difference is apparent when I switch between the 2.