domain mapping & subdomain tracking... site by site override

hey... the preview pic has subdomain tracking... but the settings dont? if domain mapping is enabled.. so is subdomain automatically? if network wide tracking is enabled? then y does each site have its own area? i assume its for the customer to check their own stats? but isn't it already on the dashboard from the networked enabled? then... does a site by site override the network enable tracking??? then... how do i turn off a sites individual settings? a few q's there.. thnx for ur answers in advance.