Here are the functions of the signposting words in italics in the sentences 1-8:

1. **Firstly** - e (to indicate order)
2. **Secondly** - e (to indicate order)
3. **because** - f (to give a reason/reasons)
4. **Additionally** - a (to give further information)
5. **That is** - g (to repeat or clarify)
6. **However** - b (to contrast)
7. **Consequently** - h (to indicate a result/results)
8. **for instance** - d (to give an example/examples)

These words help structure the flow of ideas and clarify relationships between statements.