The temporary licence is as easy as it sounds. I have had two issued now and both took about an hour and a half. The PSTAR is easy enough but the pass rate is 90% so its worth looking at it before you go. There is a great resource here -
PSTAR Table of Contents . Its worth scanning in and mailing the relevant pages of your logbook if you want the 'issued on the basis of' canadian license as it gives Transport Canada a chance to check it before you arrive at the desk. If you have a uk/jar ppl you won't have a problem. The only issue i had was for night rating as the rules differ and canada needs min 2 hrs dual night x-country. Even though i had plenty of solo night x-country i had to fly one hour dual to top up to the 2hrs required to get the night rating included. The temporary licence doesnt need a photo, but the 'issued on the basis of' does,and you have to get it done in a local drug store as it needs a stamp on the back. Don't be tempted by the one year 'foreign licence validation' as you can't add ratings to that.
The canadian medical is in theory to the same standards as ICAO generally but in practice administered in a more conservative manner. Expect qustions about family medical history and or your drinking habits !
It is worth putting the float rating on the temporary licence - I did that in 2008 and when I came back this year I got another temporary licence with that rating automatically put on it. I am just doing the PSTAR to get the 'issued on the basis of' canadian licence on the back of my uk ppl so the canadian licence will then carry that rating. I was going to do the PPL aeroplane written exam and flight test which then gives a full canadian licence but have run out of time. The full canadian licence is a peach. You can trade it for a full FAA ppl apparently (not a 61.75) and there is no separate taildragger/VP prop/complex differences training required for those aircraft types. I never bothered getting the float rating transferred to my uk licence, didn't see the point since there is so little uk float aviation.
If you are wanting to fly floats in BC I can recommend Pacific Rim Aviation, Pitt Meadows (near Vancouver) - I did my rating there in 2008 and liked it enough to go back there to do more training this year, great place. Nice 172 on floats, fleet of clean 152/172's and well run.
Hope this helps.