Ears have trouble accepting numbers and abstractions. In addition, quantities and relationships must be visually compared. When you digress from the topic of the slide on the screen, use a blank slide, colored and shaded, not white, to darken the screen. Furthermore, it will confuse your audience if you say one thing orally and you display something else visually on the screen. An outline of your major topics should be your second slide, just after your title slide.
Pie charts are good for showing relative parts of the whole.
Use standard symbols if possible. Simple schematic diagrams effectively convey the structure of systems or relationships of objects. Show only what is necessary to explain how a thing works. Tabular data is more legible and more easily compared on graphs or charts. If you must use a table, keep it simple and include only items that you will mention.