Thank you for your feedback. I'd prefer your idea with a more community centered system a lot, but the thing is... this is the way the contets were run for 7 years. When I started them it was a community driven thing: The images were discussed a lot because the contest gallery was part of this forum and there were many active users. But unfortunately during the last years the forum was visited less and less. I guess there is not much to talk about here and forums in general have a hard time because of Facebook and other social networks. So I had to abandon the forum contests because there were not enough people left who joined them. The amount of entries became way better since no registration is needed anymore.
I miss the community from the past... but since this is where we are coming from and it slowly dried out I don't see a way to make it work again. The forum has not enough members and new ones register rarely for the contests.
Regarding showing the pictures before the vote: This would be possible.
What do others thing about this change? We did not do this in the past because users were afraid good ideas might be copied. But there are two sides and I get your point.
Regarding the timeframe: I am worried less people might join the contests if there are two per month, because this feels a bit too much. I'd ask the community (or what's left of it) for their opinion... but the main problem I am thinking of is something different: To be honest I don't think I'll find the time right now to manage two contests per month. It doesn't sound like much work, but it is getting difficult for me to run the SP-Studio while also earning enough money with my daily job. And I'd prefer to focus on SP-Studio updates. It's okay for me to run one contest per month, but if a contest runs only 2 weeks this means I'd have to find time to manage it every week (start the contest - moderate the images - upload them for the vote - announce the winners). This might be possible with a wordpress plugin that can make it easier for me... but I haven't found any yet. So even if the community would prefer 2 contests per month I don't know how to pull that off right now.

For now I will test the new on-page voting system this month and perhaps there will be comments. I hope this feels more like a community again... at least more than Facebook.