When we export a vector from fireworks-in any kind of format-, is this exported as a bitmap image(rasrerized)?
Yes it's rasterized when you export to a raster image format, like PNG, JPG, GIF, etc.
It's not necessarily rasterized when exporting to a vector compatible format, like AI, SWF, or SVG (http://fireworks.abeall.com/extensions/commands/Export), but you those formats are not meant to be replacements for your source Fireworks PNG file and may not even open in Fireworks correctly or at all. Always keep your Fireworks PNG safe!
Second, when the graphic is exported and the layers are "lost", is there anyway i can recreate the layers(somehow).
I want to make some changes to an exported graphic and unfortunalely i have deleted the original, what can i do in such a case?
Unfortunately there's no automatic way to recreate the source layers from an exported image, especially a raster image like PNG or JPG. Your best bet is usually to just recreate by hand. Sorry!
Οκ, thanks for the answer.
And another thing, did you build the estension which depicted in the link you gave?
Οκ, 1 last question now i found the opportunity.
What computer language is used to make such an extension and in general for adobe suite(Dw.Fw,etc) extensions.
And there's a number of tools out there made by FW extension developers to aid in the process, for instance:
Fireworks Console: http://johndunning.com/fireworks/about/FWConsole
DOM Inspector: http://fireworks.abeall.com/extensions/panels/#DOM-Inspector