The older items cost more because they came from a different system (aka they were restockable once and not exclusive to this shop). The items that have specifically only been this shop are much cheaper! They specifically go out through quests you get QPs from, that's why Battle and MD aren't included. :)
I've adjusted the RE a few times to make it a bit more common the closer we get to the end! The last day the coins will be going out quite often!
omg BQs give out their own rewards gosh. But yeah, the people who give out QPs are those with quest shops!
The shop doesn't technically close. :) So you can save your tokens and buy things throughout the year (or buy tokens any time throughout the year from user shops so you can buy items via the New Years Shop). The old old items used to be restockable in the Holiday Shop for that specific year (like 2009 things were only available that year because a lot of things had years on them etc). By opening this New Years shop, we've brought back all those old things with years on them that wouldn't have been restocked again via Holiday Shop along with the generic new year items (fireworks, party items, etc). [edit]
HA, YOU BEAT ME. But yes, we don't' plan on retiring anything from the shop! I believe we got all the old things in there, too :D