You can keep the unoaked one in the secondary for up to several months without any issues. If you go any longer than that you may have to repitch yeast to bottle condition.
For the oak, I would start with 1oz of oak cubes and leave it on there for a week and then taste it. Keep tasting it every few days from there until you get the desired oak flavor your want
Primary1: Pumpkin Ale
Primary2: Christmas Ale
Secondary: Sour Brown
Drinking: Warrior Pale Ale, Wit, American Rye