When I am drawing in a job, the scale on dimensions and item blocks seem to change randomly. All of a sudden I will have an extremely small dimension from a microvellum generated drawing. Any clue what is going on?

In the MV Drawing Template your dimension and text scale is controlled by the scale command...  Type in "scl" at the command line and select your scale from the list.  This changes your dimension style for you automatically.  Your default template is probably set to a higher scale which would result in very small dimension text.