I have one mage in my party and its edwin he still doesnt have access to any 6th level spells or higher...hes level 11 currently is this normal what lev will he start getting some powerful lev 7-8 spells?

Check the manual that comes with the game there is a complete chart in the back that shows you which spells you will be able to memorize and cast by level. Also take note, unless you remove the exp cap, you will only be able to cast the 9th level spells from scrolls since it cuts mages off at 17th level.

14 is level 7
16 is level 8

just to name the powerful spells

7-Mordenkainen's sword(A MUST), project image(too powerful, kind of cheesy), delayed fireball blast,spell sequencer(another must have),limited wish(EXTREMELY POWERFUL, if you have 18 wisdom).

8-Abi-Dalzim's horrid wilting(up to 100 points of damage, and effective against 90% of monsters in the game), incendiary cloud(another massive damage spell),protection from energy(it's like having 80% resistance),spell trigger(excellent spell), summon fiend( A MUST HAVE).