uC to host Bluetooth module via UART
1: Other than ADC and UART interfaces, as you said, I am thinking of the memory size of the uC (so the program you write can fit on it) and its maximum clock speed.  A rate of 8000 samples per second seems a high requirement to me, so you should choose a fast uC.  You also need to take into account the ADC resolution (how much precision you need for your measurements). 

Here you see some calculations you need to do in order to know how fast you need your microcontroller to run.  They don't have the same values as yours, but you can get a picture: 
http://www.avrfreaks.net/index.php?name=PNphpBB2&amp;file=printview&amp;t=119916&amp;start=0

However there are many other things you should look in to choose a uC.  The list can be very long, but here are some hints:


Price
Power consumption
Development tools


2: UART wiring is pretty simple.  There are just three lines (GND, TX and RX) and their wiring is straightforward:
-WT12 TX pin to MCU RX pin
-WT12 RX pin to MCU Tx pin 
-WT12 GND pin to MCU GND pin

For the software it depends on which uC you are using but the code should be similar. You can take a look to any Arduino tutorial for UART communication (it is a good starting point).  They are based on ATMEGA microcontrollers.