Which tools do you use in process mapping, and if you rely on standard tools such as BPMN or you do mapping using a normal free UML diagrams. ?

Check this modeling tool : "Visual Paradigm" it is really a benifucal tool to design and model each of BPMN diagram and other UML diagrams, as too as mapping between types of models. Unfortunately it is not a free tool  but you can use a trial version to make sure the tool is suitable for your purpose. 

I think if you rely on this tool , you don't need to use any other standard tools.