As for requirements to eat food to survive, there has been plenty of discussion upon quite a long time ago. In terms of months, at least. It was regarded as \'realistic but annoying,\' and anyway, newbies are going to barely survive, and die in the, err, \'bucketfulls.\' I can\'t find the topic about food, so I don\'t have much things to tell about, not even giving the link. Anyway, being required to eat food to survive does open up some ideas, but I will still regard it as annoying, and suddently think about food rotting and NPCs/monsters having to eat to survive as well. Sometimes realistic things are not the best ways to approach creating a MMORPG.
As for having a stamina bar, I agree with the above ideas about if you run out of stamina and do things, you lose HP, and performance rate decreases when stamina decreases as well. Now for ideas on gaining stamina.
One way already discussed (I think) is if you eat, you gain stamina. Another obvious idea is resting, like lying or sleeping on a bed or resting somewhere else. Depending on where you are and whether you are sleeping, resting, sitting, standing, or other action, effects how quickly you regain stamina, as well as other factors. Example: You are in a mountain, and decide to rest on some rocks. Compare that to sleeping in a feather bed in a rich mansion. I\'m not sure whether regaining stamina will be effected by the ways I have already typed, but those are my ideas. Another idea is that you regain stamina by walking, but slowly. Wizardry 8 had that system as well.
Maybe if you perform a spell, mana will be used instead of stamina for those kinds of things, until your mana has run out. I doubt that much people will do so, though, unless they can\'t use mana for anything else.
Oh yeah, and I waa suddenly attacked by an idea while typing this sentence. I think you are more interested in the idea than how I got it, so the idea is that if you run out of stamina, you fall unconscious. Wizardry 8 also had that feature, as well as damage taking away stamina as well. I think.