As far as "official" stances on painting SCE, GW had this to say (emphasis mine):
Otherwise the general consensus appears to be that as long as you are clear with your opponent about what rules you are using, you can paint them however you want. The only possible exception may be if tournament rules state otherwise (but that will be up to the individual tournament).
In my opinion, paint them however you want. You are going to spend many hours painting, so pick a scheme you like.
And re the Hammers of Sigmar command ability - yes. However, remember it only applies to units with the "Redeemer" tag (@AdamR is right!) and you'll need to spend a command point to activate it. As awesome as it sounds, if luck is against you then you've wasted a command point.