Hi Adam,
Fellow investor from Ottawa here. Thomas has answered pretty much everything. I want to echo that Ottawa has a strong, stable and diversified job market, and looking at historic data, Ottawa prices rarely see the type of variation other cities like Vancouver, Toronto, Edmonton, and Calgary sees. In recessions, it historically has not dropped more than 5% compared to 10-15% in other markets. A book I strongly encourage you to read is Secrets of The Canadian Real Estate cycle by Don Campbell.
If you are worried about refinancing at the height of real estate value, perhaps you can look into having the refinanced equity available as a HELOC and you can use part or all of it only when needed. If you have good long term tenants, a healthy cash reserve, and the home cashflows at 80% LTV, I wouldn't worry too much about it in the Ottawa market.
Regarding capital gain, it depends on if it's your personal property or a rental, as well as your marginal tax rate. Long term, yes it's more advantageous to have it in a corporation to save on tax, however, there are disadvantages as well including higher costs (accounting costs, lawyer fees, ease of finance, mortgage rates) and, it may not as "liquid". I've heard people say it's generally not worth it under 5 properties, but it depends on your personal situation. Best to consult an accountant.