I'm new to Apple II - What can I do?

["Gary Harrison" <garyharrison@nospamidx.com.au>]

I've just been given an Apple II clone (Unitron), and apart from using one
briefly at school back in the early eighties, I've never had much experience
with these machines.

The machine has no disk-drives, only cassette connections on the back.
In the expansion slots it has a "language card", a serial card, and an
80-column card.
Also supplied with the machine were three ROM chips marked 1, 2 and 3. I
have a small expansion card with three sockets - this was not attached to
the computer though. What are these?
The machine powers up and displays "Apple ][" before giving me a "]" prompt.

Simple BASIC programs I type in work OK, but I don't know the syntax of the
more advanced BASIC commands (graphics? saving/loading?).

I'm assuming I really need a disk-drive to do anything "useful" with it?

What is a "language card" anyway? Where can I find info on Apple's BASIC?
How old is my machine exactly?

Sorry about all the questions... Thanks in advance