To answer your first question, you can modify, DimCosmetics, symbol. You can give a name (such as length) and this will show up in the family table under the D#.
You have the answer to your first question... now an attempt on your 2nd question.
How do you want to show the instance on the drawing? If you need the name of the instance you can use the system parameter with an ampersand in front to list the name of the model (i.e. model name is "bolt" - create a note on the drawing with the text "&model_name:4" (excluding the quotes of course). What will be displayed on the drawing is "bolt".
Explanation of the text: &model_name will display the name of the current model, but if you have more than one model in the drawing the software will give each model in session a suffix number. I have found that if you create the drawing with only the first model in session then the first model name is &model_name:0. The next model added to the drawing will be given the suffix &model_name:2. For drawings that have several models you will have to guess until you get what you want increasing the suffix by two (2).
Note: you have to add each model (instance) to the drawing by clicking on Views>dwg models>add model and then select the model.
I know that features also have id names in Pro/E 2001 and above, but I am not sure what the parameter names are? If you find out you will have to play the same game with the suffix.