Subscribing? If you have doubts, try LW Basic 1st so you can learn how it works. Later if you want to support the Pro development then consider it. Get it here http://www.limewire.com/english/content/download.shtml

If you have a monthly limited bandwidth for downlding, sharing will add to the total. If you don't have such limits then you're fine. Gnutella is based around sharing. That's how it works. What you find & downld is what other people like yourself are sharing. If nobody shared, there'd be nothing to downld for anybody. Giving back is a part of the gnutella community spirit.