a feather weight is just a nice little straight stitch machine- it is lightweight- which is one of it's big draws- easy to take to classes- only weighs 12 pounds. they have a (tool box) which is all contained in the case- very complete-very compact-
and they are work horses- as long as you take care of them will sew for 100's of years...a nice even straight stitch.
there is a featherweight society- you should check them out to find answeres to some of your questions- or what is wrong with finally visiting the shop and asking questions...they would probably be happy to show it all to you and tell you all about it. they range in price from $25 up to $750 or more----location matters, condition of course-the person selling it-
i would visit his shop and look at all of his machines and ask questions about them all...you may find yourself a real treasure- or you may decide what you have suits your needs just fine.