Default city/Zoom level on add listing page

Hi!
I am trying to build a global directory for marine technical service, i.e. covering the Mediterranean, Caribbean, Asia etc. So to have a default city makes very limited sense in the first place, using the user’s location as centre of the map would be ideal.

If there has to be a default city set, how can I change the zoom level of the map? A default city with a very low zoom level, e.g. 2 would work.

Would there be a way to get a ‘Near: My Location’ button to zoom to the user’s location? The code seems to be there on the search page. Most users will want to add listings at location where they are because they just got a job done and want to add the person/company. A button left of to the ‘Drag marker to location’ button would be perfect. First you zoom in to where your are, then you drag the marker. Perfect UI.

Best, ALEX