I’m just getting into empowered monos now, got corruption to ~140 so far. I’m pretty sure I can get it up quite a bit higher, but curious how high everybody else is going.
It depends heavily on your gear and build, I’d say. Personally, with a good clear balance, I run around 750 corruption (Smite Void Knight not fully enhanced gear). However, there are also people who comfortably farm with over 1000 corruption. sure, you can climb higher with the meta builds, but the main thing should be to have fun. 
I pushed to 900~ this season, but I find its more fun to farm at 500 or 600 cause its faster and i dont have to think, i get plenty of favor to the point ive accidently capped it several times now.
I’ve pushed 3 different variants of Forge Guard builds to 1000cc but I have tones of items stored so it was just a matter of testing, switching gear, getting new items etc. Idk if it would be possible in cof starting from scratch, doubtfull. Still having so much fun testing other possibilities/builds/items.
You should push to where you are comfortable clearing maps/bosses. Usually it’s between 300-600c. This season I went to 1000c, because some silly people like to use that as an argument in discussions 
Definitely.