I didn't say delete the items from your incomplete folder. Oh Oh! I said delete them from your Dwnload window (below your search pane.) If you delete the items from your incomplete folder as shown in the library window, you will delete them forever. That was not exactly following what I said. You asked for a technique to get your partially dwnlded files start to dwnld again. That was the best technique. The other is to force resume from the incomplete window, however there's no guarantees it'll start dwnlding. It must have sources available to have a good chance to start dwnlding.
You're obviously refering to multimedia such as mp3's in your next question. The bitrate is purely the rate at which the file was encoded at. For mp3 that can range from 32 up to 320 kbps. It has nothing to do with the upld/dwnld speed of the source. Quality rating is best (matter of opinion I guess). It's a good idea to go to your LW menu-Tools-Options-Searching-Quality & set the minimum at least 2 or 3 stars so that there's a much better chance of you dwnlding from reliable sources. A cable/broadband might be offering much more upld bandwidth than a T1 is offering or has available - so it depends.
But remember the bitrate that's shown in the search window has nothing to do with the dwnld speed, only the quality of the file itself. The higher the BR of the mp3, the better the quality. Anything from 128kbps up is reasonable quality.