Hi Pedro,
thanks for your interest in my plugins!
ad 1) on backend you can manually set the map center for layer maps by entering an address or dragging the layer & moving the black pin. Interaction options for maps can be set globally for all (marker and layer) maps in Settings / Map Defaults / “Interaction options” – here you can also disable dragging – but as said before, globally for all kind of maps only.
ad 2) each POI allows you to add all kinds of HTML or even shortcodes to the popuptexts – you can add a link to a post there for example.
ad 3) yes, that is possible. Just be aware that all icons need to have the same size. It is recommended to use the default size so that other icons are also still compatible. If you want to change the size of all icons globally, you have to change the according settings at Settings / Map Defaults / “Default values for marker icons”
If you have any further questions, let me know!
best,
Robert