The Fate system and stress

So I'm noting in the Fate system, physical stress is based off the Physique skill, mental off the Will skill. I'm having some trouble figuring out some details about Fate: does every character has to have these skills? Do skills automatically default to some value (0)? Should I automatically add Physique and Will to every character?

At least in the DFRPG, Endurance is the skill associated with physical stress, and physical stress defaults to two boxes, plus your endurance skill's modifier (2 boxes for no skill points, 3 boxes for 1 or 2 skill points, 4 boxes for anything above that, with additional factors for really high skill)

I don't know how it's laid out in the general fate system but the (admittedly disorganized) way it's handled in the DFRPG manual is to list how each one works in the actual skill description (so for Endurance, that'd be page 130, it'd be Conviction and page 124 for mental stress, and Presence and page 136 for social stress)

That's more or less how it works, and the reason I ask about defaults is exactly what you mentioned, that it affects stress boxes. I'm unclear on defaults.

What do you mean by defaults? If you didn't put any points in Endurance (and thus have an Endurance of Mediocre (+0)) then you have 2 Physical Stress boxes.

Yeah the Skills chapter in the DFRPG book specifies that any skill with no points assigned to it defaults to Mediocre (+0). Thus a character with no skill points in Presence, Conviction, and Endurance would have 2 Stress Boxes in each stress track.