cubase is the first one to came out from steinberg ,the se version of cubase meens less power and less plugins less channels,se is more easy to learn and its way more simple the the rest (sx1 sx2 sx3)
the plugins is not a problem you can download millions of good plugins from the web and install them , anyway cubase plugins are good but not the best ...
the latest version of cubase is sx3 wich is killer software wich i highlly recommend ! (but expensive)
if you need puging or instruments i can send you some , depends on what kind of music are you going to make ....email@example.com