Which way is the best to build a menu to those my needs? So many possibilities... (new to TikiWiki)
Welcome Ralf.
Yes Tiki is a great software with many ways and options to reach a goal.
Seems you have a project here but about your menu I have short advises.
- Don't do several levels (at least 4 to 5) ... this is not mobile friendly.
- If you want to go that way anyway use Tiki 23 : https://doc.tiki.org/Tiki23#Menu_system
- May be some ideas from here : https://tiki.org/UX-Trends-2021