Hi Thierry!

most of what you want to achieve is probably not straightforward, however - you can have a look at the openproject-my_project_page plugin, which allows individual project overview pages. It also allows for having so-called “teasers” which add custom content to the project overview, such as links, etc.)

Regarding your questions:

Different portlets on the homepage

I assume you mean the first page you encounter in OP. That would in my opinion be possible with the aforementioned openproject-my_project_page. We actually do this for https://community.openproject.org. However, we achieve this by having a hard redirect to one of our projects (the “Openproject” project) and customizing it’s overview via the plugin.

if you do not want to do that, you would probably have to start customizing yourself. The content of the homepage is located here: https://github.com/opf/openproject/blob/dev/app/views/welcome/index.html.erb You could use hard links an images. However, this requires a little bit of templating knowledge

Order of menu items and menus per module

This is unfortunately not possible to my knowledge - at least not without some programming knowlegde. The menus are currently created in a central partial and called for each view.
If you want to manipulate the menus, https://github.com/opf/openproject/blob/dev/lib/redmine/menu_manager/menu_helper.rb would be a good starting point.

New ticket link on the homepage

Same as with the portlets, this can either be achieved with the plugin or by hacking the temmplates.

Hope I could help!

Florian