I'm completely unfamiliar with the policies in either market (for example, how big of a chunk apple takes or how ads work). What are other things I need to consider?
1. The press prefer paid games/apps.
Launch your app as paid, reach the press, make some buzz and then change the price to free. With this move, lots of websites will talk about you and lots of user will want your app; but they will download as soon as you make it free.
If you want to charge for specific features, setup a in-app purchase.
2. 100,000 downloads is hard.
The first game (which is free) I launched achieved 100k downloads in the first month; that never happened again since. And it is becoming harder every day; so I would suggest that you consider 200~400 downloads a 'good enough' perfomance.
3. Banner ads suck, focus on innovative medias.
The classic AdMob banner sucks and users are learning to ignore it. Fullscreen banners, like Chartboost and Playhaven, are awesome and deliver a good eCPM ($10+). Also, Video ads (AdColony) works very well for most developers.
4. Apple's cut
They take 30% of every virtual sale; but you can sell physical products without paying them anything. Also, Apple don't make anything on your ads.
5. Android is... different
Focus on iOS, it is more predictable. Android is great, I'm a user myself; but I simply do not understand how they rank apps and how do users interact with apps.
2) What you can make hugely varies. $0-$500k+/day for serious games. It is very skewed towards top earners.
3) You'll probably have an easier time selling and developing on iOS.
Some sources for this (based on a quick Google search, one could probably find better or more conclusive sources with a little legwork):
http://www.imore.com/ios-gamers-spend-times-android-players
http://gigaom.com/apple/ios-users-buy-more-apps-and-pay-more...
http://www.macobserver.com/tmo/article/new_report_shows_ios_...
http://www.theverge.com/2012/3/31/2916556/in-app-purchases-i...
http://functionalaesthetics.eu/why-apps-are-on-ios-first-and...