Is it possible to cast Mindbar and Countercurse simultaneously, and if so does the order matter?

Answer: I am told that Mindbar can be played first, then Countercurse.

Yeap. Cast Mindbar on you, then Countercurse as many times you wish. Serenity/Purify is nulled. Currently there are ways to nulify this tactic cheaply but when the devs implement their current forthcoming changes, then this kind of combo will work better (if you see,they increase minimum turn cost of each penetrating curse to 3 from 1 that currently is).

A needed change for me as it upgrades the role of countercurse which is after all uncommon and should be stronger than it currently is.

The art of seing the sideaffects of the changes