On softcore go for a mage, 10 - 15 or so points to vit and rest int. And ofc highest int weap / armor , highest ee heal and offensive you can obtain.
To mute, I honestly think it doesn't matter, but some people say that the higher class you go the more ml it gets so you might wanna try at like monk or ninja and compare it to a feeder class. And they also say either L0 or L77 or L55 - L7x is best level to mute. But it all comes down to you and what you think fits your liking