Can I teach technical writing as a separate unit? Can I instead tightly integrate it with my regular lessons?
Yes to both. You can punctuate your regular lessons with a (weekly, for example) break to focus exclusively on technical writing, or you can carefully associate each technical writing topic with an ongoing strand of your regular work (such as writing abstracts or book reviews). What works best depends mostly on your own writing background and on your patience for finding common threads. Class scheduling (length of periods) may also make one approach more practical than the other.