When choosing a race, you are limited to the races listed in the Forgotten Realms Player’s Guide. Please consult me if you want to use another race not listed. The reason for this rule is to keep the setting as intact as possible for RP.
As a result of the above, you are allowed to pick one background from Forgotten Realms for your character.
When choosing a class, anything published by WotC for D&D fourth edition is fair game.