Yes, but it's a recently created word. You'd use it to describe something "ready or able to be launched" especially a new product ready to the introduced to the marketplace. It could also be used to describe something like a missile, which you might say "is launchable from a ship."

I have never seen or used it but it might exist in a big dictionary. If you have developed a product to a point where it is ready to be sold on the market, you could describe the product as "launchable". If you put a newly coined word in "", and it doesn't sound too silly, than you can often get away with it, especially with -able words. But I would not do it a lot or risk doing this in an exam.

Yes, the word launchable is the adjective form of the verb to launch. In addition to the examples given by others, I have heard this term used with respect to the launch of a software program and also to websites. See definition 8 at: http://dictionary.reference.com/browse/launchable?s=t

What's wrong with the word "launchable"? it sounds fine to me!