With a satellite connection, the download is usually via satellite while the upload is via phone (which is very much slower). As such, you can choose whether to go for DSL/Cable or modem. I'd probably go for DSL/Cable.

Download speed can vary a lot. Nothing wrong with what you are seeing. It is slow given your download speed - but you are using somebody else's upload speed - if someone tries to upload from you their speeds are really going to suck.

There are any number of things that could lock up your computer. It is impossible to guess what your particular problem might be.

Having said that - LimeWire can suck up a lot of processor time. The latest version (2.5.5) is more stable than previous versions. The latest JRE2 (Java from Sun version 1.4 - see the download links at LimeWire for a link) is more efficient than the previous 1.3 which is installed by default with LimeWire. (I don't know what operating system, version of Java, version of LimeWire you are using so can't be more specific).

The bitrates are (roughly) the degree of compression of the MP3 that it relates to. It may indicate the quality of the song, it has nothing to do with the speed at which you might be able to download it.

Mark