1 What's your experience? Is there some part of the rules I've overlooked?
That it is a balancing factor. Wizard's are capable of dishing out a lot of punishment. Sure, a well built character can equal a Wizard in terms of stress dealt at many power-levels, few have the flexibility a Wizard has.
A Wizard is usually capable of dishing out four spells, before taking consequences. This is usually enough for most fights, as they rarely last long in the DFRPG. That, and enchanted items can help a Wizard keep casting for longer.
2 What do you do for recovery? Tricks, hints, etc.
A mid-fight 'recovery' can be implemented at GM discretion during those big, climatic fights. However it may fit the story better for the fight to go on without pause, it all depends on the tempo.
To better manage stress, some people have a method to get the most out of the stress available. Of the four spells you can cast in a fight (without taking consequences), have the first at base Conviction + Specialisations/Foci bonus, costing one stress. Add 1 to that power for the next, for 2 stress. Have the third add 2, for 3 stress. Fourth, add 3 to the base power, for 4 stress. You can also have the first spell cost 4, second cost 3, etc. It is an 'optimised' method that makes the most out of it. Although personally I think its acting on 'OOC mechanics' too much.
3 How about a Refinement that lets you reduce the stress of a spell of a certain element by 1 or 2? Maybe have Rote spells cost less stress?
I personally don't like this idea. You can simply 'up' your power specialisation, which consequently reduces the stress a spell at a given power level will give; to a minimum of one.
4 A spell with Shifts below your adjusted Discipline costs 0 mental stress?
In my opinion, that would be a very, very bad idea. Rote's are already better then standard spells, in that no control roll is necessary. Implementing this sort of house rule, would completely break the balancing factors.
Just my thoughts on the matter.