If you are going to use the provided readings, in order to link the them, would you be able to get the students to find synonyms of the target vocabulary in the reading, or to rewrite parts of the reading using the target vocabulary. They could maybe then discuss the reading using the vocabulary. In my experience, in a discussion, this is very difficult to get them to do but they must use the vocabulary in order to retain it. In my course we had 2 assessed discussions ( case studies ) during the course. The students were told they had to use so many words from the target vocabulary to pass and this was effective in getting them to use it. Of course, I've no idea if they retained it for future courses but I would think it improved the chances.
If you are going to create your own readings, that's wonderful ( as long as they're not too difficult for the level ) but you have to consider how long it's going to take. You can't do this for every class but if you're going to teach the same course again, it becomes more feasible. If I recall, the CELTA was about 5 hours of preparation to teach 40 minutes. In the real world world, of course this isn't possible, although you should expect to spend a lot longer preparing when you begin. Adults really do appreciate more authentic material - if it's relevant to their jobs/lives/city, even better.