advice needed to build a 'Hello world application' on SaleForce (AppExchange)

we need to know how tough/easy to build a AppExchange application on [login to view URL] . The selected coder will help us in building an elementary application using APEX (sort of 'hello world' application) and will answer a few basic questions: 1. how faster is to code with APEX when compared to other tools ? Eg: DreamWeaver, Morfik's AppsBuilder, etc) ? 2. which is the skill needed in Java, PHP, you-name-it ? 3. which is the code protection offered by SF ? 4. is it possible for an AppExhange application to exchange data via SOAP ? 5. where does SF gains from hosting new applications ? 6. are there hidden costs ? 7. how does one collects money from subscribers ?