>a simple Google Map Image which shows the ordered location…
there is nothing “simple” about getting the order location based on what address people input in some form

>if someone orders something the IP-Adress will be saved…
it already is actually and i could – optionally – display it somewhere.

however, using ip addresses to identify people doing fake orders (if that is what you are referring to) is VERY simple to circumvent as well as VERY unreliable.
i can easily do 10 orders on your site from 10 different ip addresses without any effort so the above would not help you at all

> but not everyone know how to make orders from different ip-adresses

but the people who want to send fake orders are the ones that most likely do know

there are a ton of action hooks you can use for this sort of thing.

for example

add_action('wppizza_emailhtml_end','some_function');
funstion some_function($param){
echo"<tr><td>".$_SERVER['REMOTE_ADDR']."</td></tr>";
}

or something along those lines