Hi,
Really it would only take 15 minutes or so to manually configure all those sites, but you can do it faster using SQL Server Management Studio to run a query that generates the needed strings like this:
SELECT '<add key="site' + CONVERT(varchar(3),SiteID) + 'culture" value="en-GB" />'
FROM mp_Sites
ORDER BY SiteID
You'll need to click the toolbar item to change the results from grid to text, then you can copy/paste it into your user.config file
Regarding the time zone selection, are you saying that it doesn't stick when you save it in Site Settings? or are you saying it doesn't respect the site setting in the calendar?
Event Calendar Pro has its own time zone setting under instance settings and it uses that not the one from site settings.
Hope that helps,
Joe