If you check the OED, Murray, entries are given under -ize for recognize, etc.; it is the more accepted spelling.
COGNIZE- "prevalence of the ending -ize over -ise presumably due to the influence of the large class of verbs having etymological -ize."

Yes, the OED tries to be comprehensive, now including Australian, New Zealander, Canadian and other regional usage.

Syne is northern English dialect as well as Scottish, and is derived from Middle English, a contracted form of sethen, SITHEN; perhaps influenced by Old Norman. OED. The 's' sound is given.

I wouldn't presume to comment on the dialectical pronunciations.