I'm surprised you have the b00ns to keep making these bulletins.
anyways: read the lyceum article about it. It is very informative and answers all the questions you ask. The lyceum will tell you a lot; it is better to check if your question is answered there first before making a bulletin and spending your precious b00ns.
Howdy! Winter Chip typically starts in early January.
Usually, there are around 24-28 formats, though not all of them are available at the beginning. How it usually goes is that Winter Chip starts with a small number of formats, and then as time goes on and enough entries are submitted to each of the available formats, more formats are unlocked and added to the battle.
If you want to look at some of the previous Winter Chips, I recommend going to this lyceum article!
btw you’d definitely be better off joining the irc/discord chat and getting these questions answered. you’ll get a faster response and won’t have to spend a ton of boons on a bulletin.