If you right click on a host > browse host, you may be able to see what other files they're sharing.

Right click on the column header > tick 'chat'. If the host has chat enabled (you see a smiley icon), you can try to chat with them by right clicking > chat with host. Both browse host & chat don't always work.

If LW detects a corruption in a file, you might see an error message, or the download might regress.

The files are played by whichever media player you select as your default player: Setting Default video app (goes for music as well)

Are you using a good, updated AV to scan files that you've downloaded - before you open them? The files where the extension doesn't match the file type may be nasty: http://www.gnutellaforums.com/322153-post4.html

You should read the LimeWire User Guide and Frequently Asked Questions.

Also, read through the red sticky threads at the top of each forum section...they have heaps of info.