Should I use gdal_retile.py or gdal2tiles.py?

Question

I have many GeoTif files that I want to display in google earth with Geoserver. I am wondering if I want to use gdal_retile.py or gdal2tiles.py to create the image pyramids for them to be usable in Geoserver.

I am also wondering if I need to use gdal_warp on these images or are they ok since they are already in WGS 84?

Here is my output of gdalinfo:

Here is the gdalinfo output:

C:\Program Files (x86)\FWTools2.4.7>gdalinfo "c:\Users\dh\Desktop\output.tif"
Driver: GTiff/GeoTIFF
Files: c:\Users\dh\Desktop\output.tif
       c:\Users\dh\Desktop\output.tfw
Size is 4000, 1920
Coordinate System is:
GEOGCS["WGS 84",
DATUM["WGS_1984",
    SPHEROID["WGS 84",6378137,298.257223563,
    AUTHORITY["EPSG","7030"]],
AUTHORITY["EPSG","6326"]],
PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433],
AUTHORITY["EPSG","4326"]]
GeoTransform =
  -85.7491388451308, -4.524787279609347e-008, 2.666305185835285e-007
  30.00095207244157, -3.078813571247076e-007, -3.918543136581411e-008
Metadata:
  AREA_OR_POINT=Area
Image Structure Metadata:
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  ( -85.7491388,  30.0009521) ( 85d44'56.90"W, 30d 0'3.43"N)
Lower Left  ( -85.7486269,  30.0008768) ( 85d44'55.06"W, 30d 0'3.16"N)
Upper Right ( -85.7493198,  29.9997205) ( 85d44'57.55"W, 29d59'58.99"N)
Lower Right ( -85.7488079,  29.9996453) ( 85d44'55.71"W, 29d59'58.72"N)
Center      ( -85.7489734,  30.0002987) ( 85d44'56.30"W, 30d 0'1.08"N)
Band 1 Block=4000x2 Type=Byte, ColorInterp=Palette
  Color Table (RGB with 256 entries)

Answer 1

You can use gdal2tiles with the -k option to force a KML output. That will create a SuperOverlay you can open and visualize in Google Earth.

Here are some instructions you may want to reference: https://developers.google.com/kml/articles/raster

Answer 2

You don't necessarily need pyramids, unless you have hundreds of GB of data. For lower amounts of data a mosaic should work just fine, provided you add inner tiling and overviews in your data. Have a look here for directions: http://demo.geo-solutions.it/share/foss4g2011/gs_steroids_sgiannec_foss4g2011.pdf