LTC2400 datasheet inquiry

Hello, I plan to use the LTC2400 on a future project, so I bought its demoboard. I have no problem using the demoboard but I am currently in the process of making my own PCB layout for my future project. I have questions:

1. The LTC2400 datasheet mentions a 10uF tantalum capacitor. What is the recommended ESR rating? I tried checking the demoboard schematic but the 10uF capacitor was not tantalum so I am confused right now.
2. In my project, the LTC2400 will be used to measure the increasing or decreasing voltage of the device under test. This device under test will be powered by a current source. As you can see, there is a constant current directed to the device, but the device will experience a changing voltage since the device's ohmic resistance will purposely change due to something else from the design. Given this experienced changing voltage, what reference value should I use? The maximum voltage that the device shall see is about 5V. Is 5V a suitable reference value for the LTC2400? I apologize for asking since I have not had any experience with LTC2400 + current sources.

Thank you