Hi Guys / Girls
I know nothing about Extension tubes or Converters, I have the following lenses:
Canon EF-S 55-250mm IS f/4.0-5.6 lens
Canon EF-S18-55mm IS f/3.5-5.6 lens
Both standard that came with the camera.
I want to have a macro lens and a larger lens with longer zoom, I have priced both lenses up at our local shop and I'm looking at a grand for both "

"
I have been looking around the internet for ideas and methods of hiting macro and longer zoom's with out spending a fortune. These consist of Extension tubes and 2x converters "I guess".
Knowing that my lenses are not the best of the best by adding tubes and converters will this down grade my ability to take quality shots?
Will Extension Tubes really allow me to take shot's of a spiders closer than a close thing.
Will a 2x converter give me that ideal zoom range of 500mm by simply adding such an item, will I loose AF?
Will I loose my IS function?
I dont want to loose quality in my photo's "Not that I have gained any yet

" but I want the best from what my camera can do. If the above 2 items are not the path to take then I guess it would be worth while investing the money in the lenses that I want..
All advice is appreciated..