How do I automate the size setting (or any property) of both NAME and VALUE in a PCB BRD file?
There's an ULP named normalize-text.ulp which came with my EAGLE v7.2.0.

If you run it, it asks for text height and line width and will change any text in top and bottom layers name, value, place, docu and 125, 126. In addition, the parts are all smashed, as this seems to be necessary to change the text. 

If you put some text to the board manually and don't want it to be changed, open the ULP in a text editor and edit this lines:

int silk_screen_layers[] = {LAYER_TPLACE, LAYER_BPLACE, LAYER_TNAMES,
                            LAYER_BNAMES, LAYER_TVALUES, LAYER_BVALUES,
                            LAYER_TDOCU, LAYER_BDOCU, 125, 126 };


For example, you could write your texts to the place layers and remove these layers from the list in the ULP.

By the way: You can do it by hand, too: Select all devices using the rubber band tool, smash group (select smash, right-click on part of group, select smash group) and change text size of group.