Is that an other way to call for the functionality? without using the module?

No.

I would like to show the map within other places within my website. Can i call for the map with an certain command? And will i be able to add parameters to it like within the module?

Some Tips:

You can insert the module in article (or where is trigger content plugin) for example:
- create a module and set this in position custom1
- insert in article text this string {loadposition custom1}

You can override module template for adding your markers.
- copy the file modules/mod_jsnmap/tmpl/default.php in /templates/your_template_directory/html/mod_jsnmap/custom.php
- Now you can edit the file custom.php to add your markers on the map (required basic PHP/Javascript Knowledge).
- When you create a module User Map you can choose in parameter Advanced->Alternative Layout the custom.php