First of all welcome...you'll like it here =)
1. IMO the one Verizon offers. Advanced Task Killer, its free and/or if you meant file manager try ASTRO file manager
2. There's an app for that, simply search the market
3. Oh boy, there are a couple. But if you check the android apps forum, there's a thread in there where everyone lists the top 5 apps. They're there for you to pick and choose to your liking. Everyone is different.
Enjoy your stay!