Except for the crapware the network provider pre-installed, you are stuck with that, unless you root the phone or use a custom ROM. That is why I buy unlocked phones these days.
As to setting up, put the SIM card in, put battery in, turn it on and follow the instructions.
Having gone from iOS to Windows Phone 7 to Android, I spent a lot if time and money playing with apps on the iPhone, but with the other 2, I had my core half a dozen apps or so and I haven't really bothered getting any more.
Signing in with a Google account allows you to download any free apps. I signed up for Google Checkout or whatever it is called and I have bought one app.
To be honest, I use Email, Listen (RSS podcast player from Google), Audible (audio books) on a daily basis and Tweetdeck and Chrome/Firefox a few times a week. Other than that, I don't really use many apps these days.