I use Schwab Platinum as the QT quote source, but there is a long list of sources at the link below. I don't use Schwab for trading, but the quotes seem to work ok on a 2 minute "snapshot" basis. I only have satellite for broadband so my whole connection situation is kind of iffy anyway. http://www.quotetracker.com/qsources.shtml
The number of symbols you can request from the API is dependent on your previous months commission that you have generated. I am not sure of the exact formula we use, however, if you generate alot of commission and find that you are still restricted to 40 symbols then please send a mail to the helpdesk. The limitation is there because some people try to abuse the system by requesting hundreds of symbols, and not trading.