Since I going to start fresh, would programming in C# be a better learning path?
I would say not. Not that you have a choice if you are going to go with an arduino.
2. Input from pizeo resistive pressure sensor(currently 4, but may need up to 16): converted to voltage.
Not too sure what you are expecting here there is no such thing as a "pizeo resistive pressure sensor", the common pizeo sensors are voltage generators not resistive and they only give an output when the pressure on them changes, so there is no constant output.
For 16 analogue inputs you need either a Mega or a Uno with an analogue multiplexing chip on the front end. There are lots of examples of this.
3. A way to save the data recorded.
How much data, each Uno has 1K of EEPROM you can use.
4. A way to export the data,
Simplest way is to use the serial link that is already built in. Transferring stuff to the main computer is quite easy. Processing is a popular language to use.
Do kindly point me at the right forum if this isn't really a place for beginner:)
Beginners always welcome here, especially if you are willing to learn. If you just want people to do stuff for you like homework assignments then there are less people willing to do that, but their are some.