What level and IV are the bonus catch after Raid win?

IVs is the same as egg hatches.
Around 67% IV minimum I guess.

They all come as level 20 also, same as eggs as well.

It seems to follow egg rules. I'm not certain, but all my catches have been level 20 and range from 30-45 IV. Even if you and another trainer catch the same mon from the same fight, they will be unique from each other.

Its actually somewhat higher than egg catches. I don't recall specifically though.

I got a 100% IV Magikarp today from the lvl 1 raid (not shiny). Very happy with that.
They are all lvl 20, same as hatched mons from eggs once you are lvl 20 or higher.

For data purposes I've done about 10. My TTar on the high end at 95%, and magicarp on the low end at 78%. Everything else was above 80%.