A few things:
Coffeeshop Directory:
http://www.coffeeshop.freeuk.com/index.htm---
Wheelchair Accessible Coffeeshop Listings from Coffeeshop DirectoryRegarding is it easy to get around in a wheelchair - depends. Are you in a manual, or an electric? All trams are (supposed to be, and in my experience were) wheelchair accessible. Getting around - there are tons of cobblestones, tons of little hills, and tons of people. If you have an electric, you might be able to get away using the bike lanes - it'd be cute though to put a bike bell on! As for building accessibility, again I'd say it depends on your chair. You've gotta figure that the majority of older Amsterdam is not really built for accessibility. An electric chair might give you a hard time. A slim manual (and one you can do wheelies up vestibules) is going to be okay sometimes.
Regarding if people are okay to folks in chairs - I dunno, per se - but as long as you stick to Amsterdam or other large cities, you should be okay. They're used to literally all kinds there, and are happy for the tourist euros coming in. As long as you're not rude to them, they'll be okay to you. Exceptions might be around Christmas and the Royal Celebrations - simply because everyone gets a bit frustrated and harried from the influx of people.
Regarding how much money to take - it's hard to say. How long are you staying? What else do you want to do? How posh/decrepit of accommodations are you looking for? One thing to start saving up for is airfare. For me, I usually go during off-season (it's rare that it ever snows there, so whatever the weather, it's usually more mild than MN!), and I've gotten airfare as low as $450 rt, but I usually get it for about $650-$850 direct, via Detroit, or via Newark. Remember when looking at airfare - try to do any transfers within America on the way back - just makes life easier. Having said that, I got airfare via London (Gatwick at the time) and Iceland for around $550-600.