You can constrain the boundary edges or the center axis to a Reference Plane to control the location of the element.
You can control the depth of the extrusion by linking the Depth Parameter (under Properties) to a Length Parameter in the Family..
You can control the font size by going to the element's Type Properties and linking the Text Size parameter to a Length Parameter in the Family.
NOTE: Model Text can behave quite erratically when it is rotated, or hosted to a face that rotates. It will go as far as disobeying constraints and floating off the host face. This issue was touched upon in >this< thread, where I noted that Grouping the Model Text will encourage it to adhere to dimensions better.
Corey D. ────────────────────────────────────────────────────────────────────── ⁞|⁞ Please use .Accept as Solution and Give Kudos as appropriate to further enhance these forums. Thank you!