iOS receive data from bluetooth and then send information to a database on another server through wi-fi

The ordinary iOS Bluetooth APIs are only available if you enter into Apple's "Made for iPod" program. See MFi Program

If your device can use the newer "low energy" Bluetooth LE, you can look in the corebluetooth framework

There is an example of a Bluetooth LE heart rate monitor program here.

For WiFi, you can use any of several APIs from Apple and others: Berkeley unix sockets, NSURLConnection, CFNetwork, AsyncSocket, etc.

If you mean receive a string from another iOS device, the statement here about needing to be a part of the "Made For iPod" program is incorrect. This would be required if you mean you are trying to build an accessory for iPhone, iPad, or iPod.

The easiest way to "discover" other iOS devices (running your app) and transfer data between them is GKSession from the GameKit Framework. Beam It! is pretty good example code for this.

Once you initialize a GKSession just set a GKSessionDelegate and set the session's available property to YES. Check out the four required GKSessionDelegate methods and the Beam It! sample code.

http://arctouch.com/beamit/ //Beam It! code

Your best bet is to study Apple's WiTap sample app. That will answer your question #1. For question 2, you can use Apple's coredata. If you are not familiar with coredata, check out this site's tutorials.