Hi Alexej,
1. You can fill-in the name field in the properties view of a sequence flow. This will label the SequenceFlow. In addition you can set a checkbox in the Activiti preferences page to always create a default label when drawing a SequenceFlow.
2. The name of the SubProcess element can be changed by clicking on the text and do direct editing in the diagram or by changing the name field in the properties view of the SubProcess.
Best regards,
Tijs