As far as I know, you must have just one year continuos employment in one of the 29 listed NOCs. The rest of the years could be in any other NOC, but has to be full time.
When you submit your documents, whether the secondary job you have mentioned is one of the 29 listed NOC or not, you must provide Reference Letter with ALL your duties mentioned and signed by your Supervisor. Also attach your Supervisor's business card.
I know what you mean about Dreams letter. I find it confusing too. You may wait for some more responses to your query to be doubly sure.
Good luck.