You can use the following script (save it in Processing Toolbox > Scripts > Tools > Create new script) in the graphical modeler to copy the first row of attributes and apply it to each feature in the input layer.
(Unfortunately I was unable to add a filter for your required fields so hopefully others can provide a solution which completely answers your question).
##Copy shapefile and first row attributes=name
from qgis.core import QgsFeatureRequest, QgsVectorFileWriter, QgsFeature, QgsGeometry, QgsVectorLayer, QgsMapLayerRegistry
layer = processing.getObject(input)
provider = layer.dataProvider()
fields = provider.fields()
writer = QgsVectorFileWriter(output, 'UTF-8', fields, provider.geometryType(), layer.crs(), "ESRI Shapefile")
feat = QgsFeature()
for field in layer.pendingFields():
name = field.name()
request = QgsFeatureRequest().setFilterFid(0)
feat = layer.getFeatures(request).next()
result = feat[name]
for feature in layer.getFeatures():
Tested this with a simple point layer with the buffer tool and it worked so hopefully it will for you :)