Which GDC to download?

[NX via Digitalmars-d-learn]

Windows X86 64bit (x86_64-w64-mingw32)

Standard builds
Target			DMDFE		Runtime	GCC	GDC revision	Build Date
arm-linux-gnueabi	2.066.1	yes	5.2.0		dadb5a3784	2015-08-30
arm-linux-gnueabihf	2.066.1	yes	5.2.0		dadb5a3784	2015-08-30
x86_64-w64-mingw32	2.066.1	yes	5.2.0		dadb5a3784	2015-08-30

I'm totally confused about what does these mean:

1) Why there is a download targeting arm-linux-gnueabi(hf) and 
what exactly it means? Is this a cross-compiler which will 
produce obj files containing ARM instructions or what? If so, 
will linking just work? and how?

2) Is what I understand from "cross-compiler" correct? (a 
compiler that can target different architectures than the host 
architecture it's compiled for)

3) Which one to choose if I just want to write & compile windows 
programs?

4) x86_64-w64-mingw32 is commented as "Unsupported alpha build. 
SEH"? is that means windows-targeting version of the compiler is 
highly unstable/not ready yet? What's "SEH"?