2) Can you enlighten me (or suggest reading) on how HN ranks submissions? I've had discussions about some sort of ranking of papers, but we generally concluded that the sheer amount of papers published daily would make it tough to get enough (>10?) votes for being somewhat representative I imagine (for example, astro-ph on arxiv sees 50-100 submissions daily). But as you suggest, some algorithm doing preliminary ranking might help this (although it also spells danger).
For starters look at the Page Rank paper (named after Larry Page, not web page). Academic papers need something richer than page rank, but since tens of billion of web pages can be ranked for arbitrary queries, the volume of academic papers should be fime.
Ranking algorithms are one of my favorite subjects, and they are as challenging as they are important. "Search" has little to do with actual searching, it's really a ranking problem. Google's search was the first good ranking scheme for internet search, and their "I feel lucky" button was a way to show that off.
Happy to discuss by email.
In time we can hope for an HN-like system where publications are ranked immediately on publication. The algorithm would have to recognize the expertise of authorities when assigning the value of each vote. When this is possible, that cost should dissapear. But until such a system has been proven out, peer review should remain and a charge of GBP 2000 is reasonable.