Numbers 4,8,9,12,14 and 20 are the Frama, Spanish (Espana) or Costa Rican version of these stamps.
Frama is the European name for these intriguing variable value stamps dispensed from Automatic teller machines (ATMs).
Be careful as some earlier versions of these disintegrated when soaked in water. I think if yu search on here (SCF) someone mentioned these before at one time.
I like some of the designs on these. There are a lot of listings on
ebay on these 'frama' also. Some of your other one, like the interesting Thailand elephant one, could be loosely categorized into the Frama grouping. I think of Frama as those with a nice picture on them and being coloured but I would make an exception for the Thailand one.

The Canada 'cut squares' are, as londonbus suggested, off of envelopes, being pre-printed on them and sold as a whole envelope raedy to mail with stamp already on it. No licking and sticking involved. They can make a nice collection and, as Peter says, you soon graduate to wanting the whole cover.
By the way, if you do not wish to keep the frama (of any sort or just some) please keep me in mind when you reach you 50 mark and we could trade or work something out for them. They would be my first ones, that is if you are now willing to part with them.
Wikipedia article on them:
http://en.wikipedia.org/wiki/Variable_value_stamp