The volume is shown on the betting page above the the bids/offers on the match. You dont need a password to view it. Just go to the website and click on tennis and the match and it will be there. It will be there in British Pounds if you dont log in, but you can do the exchange rate. At present there has been US$500,000 bet on the Robredo/Blake match and that will multiply once the match starts.
I like using the set betting option a lot, especially when I think the dog has a good chance of producing an upset. For me it makes sense to bet against the fave winning in straight sets as opposed to the higher risk option of the dog winning outright. Betfair allows you to do this on 95% of mens matches throughout the year.
While were at it, you should look into a website called "
www.oncourt.info ", the stats this website provide are phenomenal and for anyone who bets on the tennis, this website along with a Betfair acct are mandatory.
Thanks for the kind words, thats nice of you to say. I can be opinionated at times but were all here trying to do the same thing. Happy to help in any way I can with any tennis questions.