All of this information can be found elsewhere in the forums...

Depending on your bandwidth, your downloads may be slowed down as you devote more resources to uploads. I have cable internet (3Mb/sec) and have both downloads and uploads at maximum bandwidth and have not yet been able to reach a detectable maximum (with perhaps 10 downloads and 20uploads).

When I ran dial-up internet, I was definitely more careful with what I downloaded. You don't want to waste time downloading junk! If I wanted a file quickly, I downloaded only that file. If possible, preview the download before it finishes.

Running multiple downloads simultaneously may slow down the overall process. You can control this by limiting the number of downloads.

What's important isn't the number of files you are sharing, but the number of files you are uploading.

The more sources a file has, the faster you will be able to download it (and the chances are better you will get it at all).

Finally, you cannot share programs on your bandwidth alone! You must consider the bandwidth of the file sharer. If they are running dial-up and you are running cable, you can only download as fast as they can upload.

Good luck