Does the year of publishing for corrected proofs change in the final version? I have an accepted manuscript published in an Elsevier engineering journal. The status of the article on its sciencedirect page is "In press, corrected proof". For now the article can be cited using its DOI and year of publication (2017). However, the journal is now working on two volumes: the December volume of 2017 and the January volume of 2018. I have noticed that some articles accepted after mine have been assigned to the January 2018 volume, while my article and some other articles accepted within the same week (1-7 July) are still in the corrected proof status.
So I have two question: 
1- Can the article get assigned to the January 2018 volume considering that it is now cited as an 2017 article? 
2- Is their any priority criterion for publishing? Topic? First submission date? ... etc?
Re. 1 - Yes. I have a paper that was published "epub ahead of print" in one year, and later published normally the next year. Both versions have different year numbers when cited.

Re. 2 - I would expect they do it in chronological order normally, but sometimes journals publish "special issues" on a specific topic that result in postponed or quicker printed versions. Also comments/replies to specific papers often get published in the same issue, suggesting that those ended up in print version quicker.