Hello, and welcome!
I’m not going to be able to take on this project, but hopefully the following will assist in getting you the best help available:
You actually have two (Three?) orthogonal projects going here, requiring very different skill-sets. It might be worthwhile contracting with different persons for each part.
Probably a dozen or so users here on meta that have the skill for this one.
Can you clarify what you are looking for here? Discourse already has “New Topic” on the front page, and the top of every Category page. If you just want a different positioning/style, this folds in to the Theme project.
"Hacker News Voting:"
What, specifically, would you like to emulate, and how does it differ from what Discourse offers as core functionality?
Gate access to advanced user functions, such as flagging, based on proven value to the comunity. Search “Trust Levels:” This is actually much more sophisticated than Hacker News’ “Karma Points.” The exact gating can be fine-tuned to your community’s needs.
Users can show support for Topics/Posts that they find valuable. Discourse calls these “Likes” instead of upvotes, but they are baked in at the core level. If you don’t like the icon, have it re-themed along with the rest of the Theme project.
Sort topics based on popularity: Set your default landing page to “Top.” An algorithm considers:
- Total activity in topic
- You can set a Timeframe over which the metrics are calculated, e.g. Last: Day, Week, Month &tc.
Downvotes: Search here on meta for several topics on why these are not available in Discourse core, and why a plugin is unlikely to provide them. Short version: Only “Like” stuff that is really good. If it’s not your thing, but still not bad enough to warrant a “Flag,” Simply withhold your “Like”
Hope this is helpful.