If a player has a force rating of 2 or higher, do they roll all the FR dice to determine the pool at the beginning of the game and add all symbols as pips?

If you're referring to the destiny pool, then no - Force Rating does not affect how many dice a player rolls when generating the destiny points. Each player rolls one Force die.

What @Kualan said. The Force Rating determines the pool of white dice a Force User rolls to check Force Powers (and some other stuff like committing dice and such, but mostly for checking Force Powers); it has no bearing on generating Destiny points at all.

(If, however, you're asking when a character makes the Force Power check, the answer is they do so when they want to activate their power on their turn, just like checking any other skill, etc.).

While determining the available Destiny points before each scenario/session also uses the white dice -- one for each participant player character -- this mechanic has nothing to do with Force Rating. The two are entirely different (albeit thematically related) game mechanics.

20 hours ago, Jedifish said:

If a player has a force rating of 2 or higher, do they roll all the FR dice to determine the pool at the beginning of the game and add all symbols as pips?

No, the Force Rating has no effect on the Destiny pool. However, the player's Morality score can influence the Destiny pool (if you use morality in your game).

Check the Force and Destiny Core Rulebook, pages 52 & 53.