With the zooming out it could be the Far clip plane, if you open up the outliner, select the camera you are on ie; Perspective, and open the attributes for it, then half way down is the settings for the far clip plane, just whack it up high and you can zoom out to your hearts content.Something like 10000.000 should do it!
With the other thing, not sure what you mean by scratchy, the model half disappearing could be the near clip plane, so check if that's set to the minimum it can be, I think it's 0.010, any chance of a screenshot?
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