CO.CA is new and hence there are many choices available.
It is intended primarily for companies but there is no real restriction on who can register a .co.ca. You must however be a Canandian citizen, permanent resident, company, or non-profit organisation.
There is no restriction on DNS or hosting providers.
This means that we provide the DNS servers so that you can have your site hosted by any provider anywhere in the world.
You can change or configure that any time you want.
If your name is not available in another extensions, and particularly if you're intending to use the domain for Canadian applications, .co.ca is definately a suitable alternative.