This 3.5" touchscreen is actually my second touchscreen for this project. The first was a 2.8" capacitive touchscreen that required me to solder a header onto it for connection to the RPI. My soldering skills leave a lot to be desired, and I basically ruined the first one. I purchased the second one "fully assembled" so that problem was solved.

The touchscreen plugs directly on to the RPI and breaks out the unused pins on the back. I needed three wires to read the temperature connected to +3.3V, GND and GPIO 4 (data) for the 1-wire to work.