Can I reuse parts of a chapter from a text book in my thesis?
I did this in my thesis - my introduction was going cover a lot of information overlapping 3 textbook chapters I'd written, and I really didn't want to write it all again!

I did check with the publisher first, however (just an email asking for their consent), and added an acknowledgement to them in my acknowledgements page. I'm sure this was probably over-zealous, but it felt better to err on that side of things.