1) Usually, yes. It has additional height that gets it out of some of the ground clutter and further away from potential noise sources.
2) The one that works and fits in your attic is the "best" one. It may take several attempts to find that one.
3) Possibly. It would be necessary to give it a try to see how it does. Attics are unpredictable, more so than indoors.
We have a "generic" attic installation tip sheet on our web site at
http://www.antennasdirect.com/attic_installation.html You may find it to be useful.