Changing Dimensions Data by operators

no I dont think this is possible  but a vba programmer could create such a thing it would however  require you to put an attribute into the pipe  element ..or tell it  what to use

One suggestion I could make  to make this easier  for detailing is to only put pipes on levels named by their diameter ie 250 pipe, 300 pipe then you could at least see all the 250 diams or move the mouse near element and flyout would tell you  even so your still going to have to add that either manually or edit the secondary dim..

The edit could be sped up with some variables that create some custom custom constants Bob Mecham  from Envision Cad has publish a tutorial on just this feature for the pop calc  in the latest issue of Control Alt Delete

see his articles here

envisioncad.com/.../customizing-values-in-accudraw-popup-calculator

it may be of some help or not .. I havent tried it yet...

not sure if this is anything that can help you out on your 1st question:

in the text editor you can right click and chose 'insert field'. In the field type you can add 'element properties' which allows you to chose an element and chose an element property from a list (which could allow you to get info like the diameter of a pipe.

You can also add a prefix of a suffix (like units: mm)  and even use a conversion factor. This would allow you to write the '2x' in the editor and use a conversion factor 0.5 to write:

"2x 3600"

in stead of:

"7200"