Hi,
1.) These are "special" detents - when you fly a go-around, you will retract your flaps to 15 for a normal approach and to 1 for a single-engine approach. The gates make it impossible to move the levers past these detents "by accident". A safety feature.
2.) There is - but you need a second crew member in the cockpit to say it (just like in real life). There is no automatic callout. Maybe ask your wife, or your brother... ;-)
3.) That is correct - we are thinking about implementing something for the avitab that allows reading the checklist (you can also manually add that .png into the avitab folder and access it there).
Cheers, Jan