wireless question

> I have a Realtek driver in my laptop which requires non-free firmware. I
> want to just bypass this driver altogether.

Trisquel will probably just ignore the card if it cannot use it without
the non-free firmware.

> Can I buy a USB wireless adapter
> in a retail store that will work with my laptop?

If they use supported chipset (for non-USB adapters there could be
more possible problems). Remember that different versions of a single
device might use completely different chipsets and not all stores
specify the version (but it might have other devices known to work with
Trisquel).

> I see the list on fsf.org
> of supported drivers/cards but I am confused.

A different list is at http://h-node.com/, it has data added nearly
only by Trisquel users and is newer, so it might be also useful.

> Does the USB adapter have
> everything I need on it?

Assuming you want just to connect a Trisquel laptop to a wifi network,
yes (unless it needs a non-free or very new free driver).

> Where do I get the driver file?

Trisquel already has it in kernel or its modules, so you don't need to
get driver files.

Basically if the card doesn't work w/ all free software if you plug it in it simply will not load. Unless like Michal said it is a very recently free'd driver and just simply hasn't made its way into the distro but that is the exception to the rule.

See this h-node website (http://www.h-node.com/wifi/catalogue/en/1/1/undef/undef/yes/USB/undef) and these USB dongles WILL work. I have one of them and it was simply plug and play.