Understanding FAST search versions

Question

FAST search seems to come in several flavors including: "FAST Search Server for Internal Applications" (FSIA) and "FAST Search Server for Internet Sites"

Are these separate SKUs? Are they available on MSDN download for universal subscribers?

Also what about "FAST Search Designer for Microsoft Visual Studio"?

I am trying to evaluate if I can use FAST to do web crawling with data mining and text analytics; so far I have been unable to find any simple and clear explanations on the web on how to go about doing this.