I clerked at one of the top 3 firms and had interviews with 7 firms all up (5 top tiers, 2 mid tiers) last year. Not sure about all your questions, but hopefully I can help.
1. Each firm will have a different cut-off, and some may be more flexible about this. It's pretty impossible to find...
I did a 1.5 years of a combined law degree at UTS and, for various reasons which aren't really relevant here, I'm finishing off my law degree at Usyd (graduate law) so I may be able to give some insight.
I had a couple of friends at UTS who dropped their second degree midway through and just...