1. Yes, hold shift and click where you want a unit or units to go, and let go of shift and click on the last spot you want the unit to go and it will go to those way-points
2. Yes, pick a unit, units, building, or buildings (best for turrents if you want them all to attack one thing), hold control and press one of the number keys from 1-9 to set that group to that number, then press that number to get that group.
3. I don't know