Canadian working for and out of Canada wanting to live in Spain: what will happen

Hello,

I am a Canadian (that also can carry a British passport) and will continue to work for a Canadian Company (ie get paid T4) ect. But I want to live in Spain, therefore not looking to get a job in Spain. Can I do this, how long. Can I get Spanish Health, etc.
The reason is that the company I work for (large tech company) may not be able to easily transfer me to Spain, I am working on it. I am looking an understanding of tax etc. I do not own a home in Canada, currently renting. I have some RRSPs and Stock. I obviously would sell my car. But will have to maintain a Canadain Bank account for Payroll purposes.

Am I limited to only be there for 6 months? Or will I then have to pay tax in both countries, I am bit confused by the tax agreeement between Spain and Canada. Would it be easier if I had a british passport? I am a Canadian Citizen but born in Scotland.

Any insight would be welcome.

thanks,

Campbell