I always pick up everything and salvage or sell, just so I don't have to worry about not having enough money or mats to do upgrades later.

I get the sentiment though. In World Tier 3 at lvl 55, your loot drops start getting capped pretty heavily in terms of stats. I was pretty much getting garbage loot, even if they were sacred, and I got to a point where I was just blindly salvaging all rares and most legendaries unless they had aspects that were right for my build.

Definitely. Soon enough you will be picking up only ancestral or better and only flawless gems or better.

It's really up to you. The non-sacred rares are pretty much useless except to salvage or sell, so if you're after money or materials then it's still worth picking them up. But if you're specifically looking for gear upgrades then there's not much point taking non-sacred items.

I'm at the point in Torment that I no longer bother picking up non-ancestral item drops. Same with gems - I have so many that there's no point picking up yet another bunch of flawless gems.