ODAG apps allow section access. There is no need to generate more than 1 template app if you you have section access in place.
If you are not using section access - than yes, you would need to have more applications. Maybe document chaining here would be a better option for you? Not sure, as I don't know the full requirements of your project.
And yes - all on-demand apps reload normally; on-demand using the selections submitted in selection app or ad-hoc by accessing the script editor in each template app.
Hope this helps at least a little, good luck!
Can't really make use of section access, since Qlik App objects will be injected into webpage via one authorised user only. That means I have to cut-off data for them previously. Of course I could made a pre-selection, but there are some security issues here - anyone with half of a brain can change the selections in URL Thats why ODAG is better here - it simply doesnt conain any more data than its already needed...