You have the right objective and tube lens. As @tkircher says, the 100x objective needs to get very close to the sample. You will need to have your slide with the sample and cover slip on the underside so that there is only a thin coverslip between the sample and the lens. With your Raspberry Pi lens the working distance between the lens and the sample is a bit more than 1mm, so you will have been able to have a sample on top of a standard microscope slide.
The 100x lens is designed to work with immersion oil between the lens and the coverslip over the sample. You should be able to get an image without oil, but it will not get the full resolution and it will probably have various aberrations in colour or focus. If you need the highest resolution, you will need to use immersion oil, if you don’t need the very highest resolution then it is usually best to use a x40 or x60 lens which give the best resolution that you can get without oil.
For your other question, the the field of view of the basic optics with the Pi camera lens is similar to a x20 microscope objective in the high resolution optics module (Comparison of a pi-camera and a 20x optical lens - Contributions - OpenFlexure Forum). So the 100x lens will be about five times smaller field of view.