1 and 3. This jam requires you to have 20+ rates. Itch.io algoritm also penalize games that have less rates than the median (but it probably doesn't matter because of the 20 rates cap of this jam).
2. This jam only allows game breaking bug fixes.
4. By default the "submissions" page is random, so just rating games doesn't help you getting more rates. There is a "sorting by karma" option that sort according to number or rates and feedbacks posted, but idk how many people are using it as it is a bit hidden. I think the best way to get rates is to write feedbacks and hope that the dev rates you back.