2.0 vs. 1.8.5 doesn't really matter, just use 2.0, it doesn't affect anything besides maybe slightly slower loads, 2.0 is still current patch. It just means that 1.8.4 and below aren't allowed because they have more glitches.

You just use the downpatcher that's on the resources. https://www.speedrun.com/bl2/resources https://drive.google.com/file/d/1pszuaLQVNEjCvkchZYan2eQconKskKwU/edit