1 - Yes, sort of. The LiveCycle products require the LiveCycle foundation classes to run, but you don't need to install the other modules (Forms, ReaderExtensions, etc). With Generator you will get some "common" modules, such as Assembler. To merge two documents in the manner you mentioned, you will use Assembler.
2 - Yes. LiveCycle modules run on a J2EE platform and have a full Java API. The client jar files come with the product. Java Documentation can be found online at:http://help.adobe.com/en_US/livecycle/9.0/programLC/javadoc/index.html
Samples can be found at: http://www.adobe.com/devnet/livecycle/samples.html
3 - Price and licensing are too broad a topic to discuss in the forums. It will depend on the request volume (which effects the # CPUs), corporate discounts, existing Adobe products, etc. Your Adobe Sales Representative is best qualified to give you a quote based on your needs.
Thankyou Hodmi for your quick reply.
one more thing to bother you...
can I get some sort to trial thing of livecycle Pdf generator..??
I need to do a POC(proof of concept) before I suggest my client to buy this software..
If there is a trial version of PdfGenerator Please let me know.please post the link..
You can download LiveCycle ES2 from trial software on Adobe website and try it out. This includes other modules of LC, but you can choose to install only PDF Generator. You do also need Acrobat Pro Extended, which is also available as a trial.