We're a city of almost 1,000,000 people and the national capital so thought I'm not an expert I would say that we should have a pretty strong market. Much would demand some local/industry expertise so it may be a little challenging. If you do come, I think you'll be selling your research and writing skills to show that you can quickly learn about a new topic and distill it down to an interesting, informative piece of writing.
You might do well to secure contracts in Italy before arriving, writing about Canada/Ottawa for Italian audiences might be easier.
I'm not an expert on the immigration requirements. I think you'll need a work visa but all the information that you need should be right here at the Immigration Canada website.
Writing isn't really my field of expertise so I'm not sure how much more I can tell you. I was able to find this site.
If you have expertise as a technical writer you can often find jobs posted through the local employment agencies. I've found this one to be good, (with search results for writers included)
I guess one more thing: winter. Our reputation is well-earned. There isn't much to prepare you for an Ottawa winter - amongst the hardest in a country known for its hard winters. There's lots of sunshine, but that also means many days of -20 celsius. Once we're in the depths of winter we're pretty happy if the high reaches -10. There are many wonderful things to do as we really try to make the best of it, but if you have any concerns about that it may be best to wait until Spring. If you're coming in the winter, plan to spend two or three hundred CAD on a good winter coat and boots. Winter can be a lot of fun here but you've got to be dressed for it.
I'm sorry I can't be more helpful but I hope that this at least advances your search.
I wish you the best of luck!