Hi!
The grunt dev task is watching for file changes for the framework. So waiting means in this case: "waiting for a file change". If you change a file in the framework the watcher reacts on it and creates a new version of the framework.
Some more Information on this topic.
a) the generator builds the framework to the .tmp directory (inside the framework github clone directory)
c) if you use the generator-m and you want to use your own builded framework do the following:
1. inside the app folder: app/bower_components/themproject/ remove the dist folder
2. create a link to the dist folder to the dist of your clone of a)
cd YOURAPP/app/bower_components/themproject/"
rm -rf dist
ln -s /PATH/TO/The-M-Project/.tmp ./dist
d) the grunt dev task can also be run as grunt dev-js or grunt dev-css to watch only the js/css files
If you have any further questions don't hesitate to ask.
best regards
marco