there isnt really a mana curve since you can draw what you want when you want (ie you wont be upset to have a high casting cost in your hand in the beginning)
you can build a deck around really high cost spells, but you will be saving mana longer to cast them. add in extra channeling.
as for the % of spells. i figure about 30ish points of your deck (about 25%) should be reacting to what your opponent is doing. how are you going to deal with enchantments, how are you going to deal with equipment, etc. also your main defences go in this catagory. blocks, nullify, etc.
the rest is your build, what do you want to do and how do you want to do it. ive made builds with no attack cards that work. it just depends on what you want to do. my advice would be to start general with a little of everything and play a few games and see how it works.
its interesting in mage wars its not just whats in your book its how you play it. it is possibly to make a book that has 2 seperate distinct strategies. this gives you the flexability to change strategies based on who your faceing, or even change mid stride if one isnt working.
for example i had a melee build warlock that found himself all decked out with melee attack and ended up with 6 weak counters he couldnt get rid of, redicucing his melee damage to 1 die attacks. but i had an elemental wand and some fire spells, plus nullify to protect it from a disolve, so i ended up winning that game.