How to find out if a Canadian cellphone works abroad? [duplicate]

First, look up the phone's specs via Google. Wikipedia has good pages for most phones, including yours, and the top right infobox says:

Compatible networks GSM 850/900/1800/1900, EDGE UMTS 900/1700/2100

Ignore the EDGE UMTS HSPA LTE OMG BBQ WTF bit at the end and look at the first part after GSM: you've got four numbers (frequencies) listed. Geeks calls that "quad-band", but in English, that means "works everywhere". Broadly speaking, the Americas use GSM 850/1900, while everywhere else uses 900/1800; as long as you've got at least three of those covered ("tri-band"), you're set, at least for voice calls, SMS and some sort of basic data.

This is pretty much the default these days, as (at the risk of slight oversimplification) most modern cellphones have solved the problem of multiple incompatible standards and frequencies by simply supporting everything. The main outlying non-GSM standard is CDMA2000, which is (roughly speaking) useless for roaming, but fortunately that's dying out -- check this list, again on Wikipedia, to see if you're stuck with it. (If you're in Canada, odds are very high you're not.)

And as for your last question, if your phone is unlocked, it will accept a local SIM -- that's what unlocked means! If you plan on using your phone for more than a day or two, local rates will always be better than roaming.