Yeah, your teaching pro is correct. You should try to align your left arm and club at setup and again at impact. It helps for 2 reasons: in your takeaway (which is why the address position is important) the club and left arm stay connected and the second advantage of doing this at address is to ensure your hands are ahead of the golf ball.

The same position at impact aligns a firm left wrist with the club that is ideal to deliver the impact blow.

Quite correct again, each club differs and the longer the club is, the less forward lean you want.

__________________
Golf is easy ... once you know how.
Graham Arnott, teaching professional
Kelrosa Golf Studios
www.kelrosagolf.com
Class 'A' PGA Member
Full Member: World Golf Teachers Federation (GB&I)