Does the recent Earth-hour event staged over the week-end actually save money? When the event occurs there is a major drop in energy consumption at the start but isn't there also a spike when everyone turns items back on at the end of the hour?
Did you see something specific regarding a claim of money saved through observance of the Earth Hour event? The organisers maintain it is about raising awareness of climate change issues - I can't find anything from them regarding saving money/have never seen anything.
You could take the claims regarding drops in national-level energy consumption and the decrease in use of various items/devices etc etc and work out a financial savings of a sort - ie. add together "energy not used x average kilowatt cost", "fuel saved through non-use of vehicles x average price per litre", etc etc and so on. But it would be wild wild guesses littered with assumptions - I seriously doubt you could work up a credible figure.
Which is why I don't think the organisers make claims regarding money (please correct me if you saw something from them that stated otherwise) - they tend to stick to the "awareness" mantra.
Regarding your second question, I think you'll find there is some consensus that large-scale downturns followed by large-scale upturns in electricity consumption is not environmentally friendly. The Telegraph is a good read on this: http://www.telegraph.co.uk/earth/environment/climatechange/7527469/Earth-Hour-will-not-cut-carbon-emissions.html (To be honest, the Telegraph's article is a good summary of the entire concept of Earth Day.)