First iPhone, what should I Do? So, I've decided to go for an iPhone 4. But since I am new to the whole iPhone thing, what are the things that I should know, to make the maximum use of the device?

Some of the questions I would like to know the answer:


what are the apps I should install? 
How do I charge the battery? 
The temperature the iPhone should be exposed to in order to prolong the lifespan?
1) That entirely depends on what you want to do. There are a bunch of app recommendation discussions here based around games, productivity, etc. Rather than rehash them, I'd suggest searching those out.

2) Plug it into a USB port on your computer. The phone also comes with a wall adapter for the USB cable so you can charge it from a wall socket.

3) Don't stick it in the oven or the freezer and you should be fine.