Driver Development in Linux

Hi, i am new to Linux World. I wonder something. When i have a google search about any device driver based on linux, i come accross several of them supplied by different Hardware Vendors.

What i wanna know is:

1. Is the linux version important? Does a chip, supporting v2.6, not handle a device driver supporting v2.4?

2. Do the chip vendors which claim to support linux OS, also supply Hardware Abstraction Layers for any device driver?

I will be hapy, if anyone can inform me about these...

Per your first question:
The kernel version is very important. The interface presented to drivers is vastly different between 2.4 and 2.6. If you are running a 2.4 kernel, you need to compile from a source written for 2.4