This sounds like chemical engineering! 
I'm assuming the pH and conductivity sensors interfere with each other if they are in the same solution, and that the force sensors determine the mass of 2 vessels (that maybe you are mixing?) And the Pi runs a graphical UI?
Arduino programs (they are not, in a technical sense, scripts) can include different parts, and are written in C++ coupled with an Arduino library that provides descriptive function names for interacting with Arduino's hardware. They are usually clock driven programs, that run repeatedly. It's a pretty neat system for controlling machinery that does the same kind of thing over and over.
Sending a serial string is one way of transmitting data. rPi also has a bit of gpio capability, so perhaps a more complex interface would give the best performance. It might be best to have the Arduino turn on and off the electrical sensors, and hold the two data until you are ready to send it to the rPi. In fact, a lot of data conditioning can be done on the Arduino, which would simplify your Pi code. Reading the EC & pH takes a couple analog to digital conversions, so the data generation should complete in a quarter of a millisecond, give or take, plus however long to read the sensors for.