I have questions about them.

1. How do you change the way they go? If you take them into your level, you'll see an arrow pointing where they'll come towards, or swing to.

2. Is it possible to expand their size? For example, opening up a path.

no and no, it's only used to reveal portal surfaces.

It just toggles the portability of the panel (true|false). For opening paths you may want to try angled panels which are start-deployed and undeploy on a certain trigger.

For angled panels: rightclick them and set their angle, then connect them to whatever needs to control them. Go back to the panel again and check "start deployed". That way you can reveal a new path