UK Citizen with PR status back living in the UK

Hi

I am a UK citizen and have PR status (skilled worker) in Canada from May 2011-May 2016. Having lived with Canada from April 2012-June 2013 (ie 13 months), I moved back to the UK with my Canadian fiance who is on a Tier 5 YMS visa in the UK. We are due to get married in March 2014 so technically via the spouse of a Canadian citizen abroad, I would meet PR renewal 730 day obligations. However, we are planning on staying in the UK (at least for the short term) and only travelling back to Canada to visit her family. At the moment, we don't know if we would ever move back to Canada so I want to leave our options open

So a couple of questions:
1) Is it better to let the PR card run its course and then renew the PR card when we decide to move back in 3-4 years? Or should I revoke the PR card and reapply for a new one (this time under spousal) to when I actually need it? How do I revoke it from outside the UK?
2) If I did let the PR card run its course and still live within the UK, as I regularly VISIT Canada to see my fiances parents, would I have problems on entering so should I revoke it?
3) If it's better to RENEW the PR card, how do I do that from outside Canada? I believe I can put in a Canadian address but Im unclear how to get in the country if ever they ask for me to collect the PR card in person or ask for an interview if I'm working in the UK at that time
4) Following on from point 3 above. Unfortunately I dont have a lot of bank statements/letters left from my time in Canada from April 2012- June 2013. What other evidence can I use to prove? I know some of the flight numbers etc but I don't have a stamp for every entry/exit as border control is pretty inconsistent with stamps

I'm basically trying to figure out what's the best thing to do with my almost expired PR card to ensure I can reapply for a new one later down the line if we were to move back (via my future spouse) but also allow me to visit Canada in the meantime whilst living in the UK

Thanks