What you can and can't do will to some extent depend on what Amiga you're going to be using.
Developing stuff would be a lot easier with a hard drive (I suppose nowadays we should also include other storage mediums) and extra RAM.
A plain 500 will limit your choices, a fully blown 4000 will give you nearly limitless opportunites.
There's loads of variations of Basic out there for the Amiga, AMOS, PowerBasic etc and , C++, E, Forth and other such languages.
Googling the WEB should help you find documentation on manuals etc.
If you can give more specific information on what you'd like to do - we could be more helpful ;-)
Dave G 8-)