Converting BML to TT and routing in the presence of a widget

[pauamma]

The workflow given in http://wiki.dreamwidth.net/wiki/index.php/Routing_and_Template_Cookbook:_BML_Conversion_Workflow doesn't indicate what to do when you find yourself in the presence of a widget, like for htdocs/support/submit.bml. Some questions an addition could cover:
- Can/Should I use the widget itself directly in a controller?
- Which parts of the widget need to go where?
- When is it safe to get rid of the widget itself? (eg, how do I know it's not used anywhere else)

I probably forgot some questions/issues. Discuss here and I'll try to summarize to the wiki?