Urban Gardening

I'm downsizing from a 3 bdrm town home to a 2 bdrm apartment and need some ideas on how to plant a garden on a balcony.

4 X 8 foot balcony with a solid concrete railing and direct sunlight from 7am to 7pm.

Here's what I have planned so far:
- Herbs potted indoors.
- Hanging tomato plant (will this work with peppers too?)
- Onions and Garlic in a railing planter

Composting is also a concern, if you have any ideas.