import arcpy, os
arcpy.env.overwriteOutput = True
# Workspace for interchange files
arcpy.env.workspace = ws = "C:\_Planharv2017update"
# List all ArcInfo Interchange files (.e00)
for cov in arcpy.ListFiles('*.e00'):
arcpy.ImportFromE00_conversion(cov, ws, cov.split('.'))
print 'Converted %s' % cov
You are exporting to a folder, this means the outputs will be shp files. I recommend creating a file geodatabase and putting your intermediate results there.
To append data to an existing feature class you use the Append (Management) tool.