Thanks for reaching out and gathering thoughts on the jam
1. While the exact deadline isn't a huge concern for me, having at least two weekends included in the submission period is ideal. I believe many participants, including myself, only weekends to properly do focused development.
2. I agree that the frequency of game jams is important, but it's more crucial to choose dates that align well with the community's availability and major events or jams. AKA: to have a "Jam calendar" in advance. Personally, my time to participate in game jams is a bit limited, so I'm not sure I would be able to join every 3 months.
3. I really appreciate having a prize as an incentive. Especially because it can work as a way to bring the best game(s) to Steam as a free game (paying the 100$ fee). The ideal solution would be to find a sponsor who would be interested in putting their brand forward for a few bucks.
4. Awesome, I'm eager to see the judging stream!