I guess I was mainly trying to say that the Linux version was similar to the Windows version, it's not Windows-only as the previous comment indicated. But right, your other comments are all valid.
Actually the build chain for both Xilinx and Altera works quite well in Linux, in fact I have heard that some consider it superior based on memory management issues.
Modelsim is available on Linux as well, but only their more expensive SE product. They charge a premium for Linux platform.