Assign location from Profile2 to a node I would like to allow user when creating new content (an event) to assign (from drop down) one of the locations defined in his profile (Profile2)... Is there a module which could help? If not any hint how to solve it in custom module? 
Im thinking entity reference field could do if it was possible to create list of location for each user... 
Maybe it is simple but beyond my drupal skills... ;)
Locations are nodes referenced with entity reference but not necessarily created by the same user
Install the references module, once you done that, you can enable the node_reference submodule and attach a "Node Reference" field to your "event" content type. Choose the "select list" widget and the user will be able to link any location to the event.

If you want to let the user choose only from locations he created, here's a way: 

On the field configuration page, you can see a fieldset called "Views - Nodes that can be referenced". It says that options from the dropdown can be filtered based on a view using the "References" display type.

Just create a view listing location nodes and select the correct "display type" as shown below:



And display nodes from the current logged-in user by adding a contextual filter "Content: Author uid"



Save all that and refresh the field configuration page. Select the view from the dropdown list that just appeared and you should be good to go ;).