entity_metadata_wrapper

Despite reading some documentation and looking to google on this subject i don't achiev to do the job ...
severals thing dont' goes well :
1)
$wrapper->my_date_field->value()
gives me a timestamp and not a datetime object.
2)
i can't find a way to get the value2 in my field
$wrapper->my_date_field->value2
$wrapper->my_date_field->value2->value()
$wrapper->my_date_field['value2']
$wrapper->my_date_field['value2']>value
doesn't work.
3)trying to set the date is a problem too
$wrapper->my_date_field->set()
$wrapper->my_date_field->value->set()