Some Feat notes:
Great Fortitude: +2 FORT (+3 at 11th, +4 at 21st)
Implement Focus: +1/tier damage with proficient implement, can take more than once
Improved Defenses: +1/tier to FORT, REF, WILL
Iron Will: +2 WILL (+3 at 11th, +4 at 21st)
Lightning ReflexesL +2 REF (+3 @ 11, +4 @ 21)
Resilient Focus: +2 to Saves
Skill Focus: +3 to a skill, can be taken more than once
Superior Fortitude - req STR 15 or CON 15, gives same as Great Fortitude plus resist 3/tier ongoing damage
Superior Reflexes - req DEX or INT 15, same as Lightning Reflexes, plus gain CA against all enemies during first round
Superior Will - req WIS or CHA 15, gives Iron Will benefits plus save vs. dazed or stunned at the start of your turn (even if an affect wouldn't normally end on a save)
Weapon Focus: +1/tier damage for a weapon group, can take more than once.
There's no reference to old feats, either to allow or disallow or replace or include them. The Essentials books seem like a self-contained subset that makes up a complete game, but are compatible with the "greater game" as it were.