The user Guide tells you what the symbols mean: User Guide Search Basic - LimeWire

Here are some links with info about how to search etc... Bitzi's a site where users can rate files, so that other users can check the quality & content. Music isn't rated as often as movies & programs, but it's still worth checking!
How to use Bitzi

Fake files showing up in search results

How to find music(tips for movies, too)

You can preview your download, to make sure it's the right file & sounds ok. Wait til the file's downloaded ~ 20% & then click the 'Preview' button. If the file isn't what you want - kill the download.

You need to make sure that you're using a good antivirus program. Keep your AV updated & use it to scan every file that you download - before you open the file

If you're new to LW, you should read the LimeWire FAQ and User Guide