I have used my 196 in a Firefly with no problems, I do sometimes have to shield the display with my hand if its very bright.
The Garmin updates are monthly, and coincide with the global AIRAC cycle. I seem to recall that they are about 25.00GBP per update. Check out the Garmin Website. If you only do it once per year, then airspace updates, such as the recent Bristol one, wont appear in your database!
Cheers
M