TOPIC: Critical path and lead/lag

Can you please confirm if my understanding is correct ?

1. Addition of Lag on Critical path can increase the critical path duration (critical path remains same).
2. Addition of Lag on non-critical path can make this new non-critical path -> critical path (critical path changes)
3. Addition of Lead on critical path can make critical path -> non-critical path. (Another path in the n/w may now have longest duration)
4. Addition of Lead on non-critical path has no effect on current critical path.

For achieving fast tracking (schedule compression) to achieve project deadline one can use
1. Lead
2. Removal of discretionary dependency

#1: Correct, because the critical path typically has zero float.
#2: CAN (but doesn't have to). It could be ANOTHER critical path (you can have more than one).
#3: CAN (but doesn't have to).
#4: Correct. You are just increasing the float.

#1-2: You can also use fasttracking and crashing.

Crashing - increases costs (more people / overtime).
Fastracking - increases risks (we are painting and laying carpet at the same time)
Resource Smoothing - (adjusting resources so nobody is working over say 85% productivity).
Resource Leveling - adjust start / finish dates to adjust resource supply with demand (** can cause critical path to change)