Re: How can you feed this many people?
I'll just answer en mass, I can see the points for why bill would have asked this question. The only reason I bring up the magic handwave is because it is specifically mentioned this is a high-magic game.
My assumptions of high-magic are; there is a large and diverse population of casters (some friendly some not, some players some not), magic is very common and not a "suprise" tactic, magic is quite often used as a substitute for technology. I'll explain my reasoning.
High-magic in my mind brings up the ideas that nearly everyone you come across, while not a caster, has some magical item or trinket they use. Wallets that always give you the correct change if you have put at least that much inside, glasses (magical not technical) to fix eyesight, the backpack that holds almost anything, etc.
That leads directly to the idea that if everyone has magic, who's going to be suprised by it? "I've got The Sword of Dancing." "Well I've got the Armor of Singing. HA!"
If there is a large population of magic users around the city is going to organize or hire some of them to help with civic projects. Not every caster is going to be Elminster. More than likely quite a few will have a more practical slant to their magic. "Look our lamps never go out." "We haven't had rain in 30 days... hey Wizard can you summon us a storm?" Why would a society ever learn to build skyscrapers when there is someone around who can chant some words and make a building from a pile of rocks?
I might be thinking a little too "HIGH" in my high-magic thoughts, but that's something that only bill can answer.