Nice suggestions!
In accordance with Brazilian (and French) Army aviation TTP (i don't know these procedures at Russian Army):
1st Group of Speed: less than 30 kt (low lift, high torque and power)
2nd Group: 30-80 kt (high lift, medium torque and power)
3rd Group: more than 80 kt (high lift, high torque)
- NOE: 10-15 ft
- Contour: about 50 ft, direct route
- Low level: 100-200 ft above the highest obstacle, max speed
Cruise is not a terrain flight.