1. No, the two processes are completely different.
- A Flee Reaction happens when charges are declared: in that sub-phase, your roll the distance for and actually move the fleeing unit. However, at this point, the charging units does not roll nor move. Other units may also declare a charge against the fleeing unit, which would then need to flee again. Only after all charges have been declared, the charges are resolved and you roll the charge distance for and move the pursuing unit(s), which must come into actual contact with the fleeing unit to destroy it. Even if the charge roll is higher than the flee roll, the fleeing unit is not destroyed, if the charging unit cannot contact it (e.g. because of intervening units - hence the double flee tactic).
- In the case of a Break Test, you first roll to flee and immediately afterwards roll to pursue: "if the victorious unit's pursuit roll is equal to or greater than the Flee roll scored by the fleeing enemy unit, the fleeing unit is completely destroyed where they stand" (BRB p. 56)
Only if the flee roll is greater than the pursue roll, you actually move the units. In that case, BRB p. 58 specifies: "If a pursuit move would take the pursuer into contact with an enemy unit, then the pursuers must charge the enemy unit. (...) the charged unit is taken by surprise by this impromptu assault — it is not allowed to take any charge reactions and must Hold. (...) Even if the charged unit was already fleeing, it still cannot take any charge reactions. Move the pursuers into contact with it as you would for a unit completing a charge against a fleeing unit (see page 23). The fleeing unit is then immediately destroyed and the pursuing unit is allowed one final reform."
2. Yes.
