Everything you find in 32 bit is also in 64 bit. All libraries are availble as 32 bit and 64 bit for the 64 version. Some apps are also avaiable as 32 bit for 64 bit installation by default (without enabling extra repos).
I am not a lawyer.
Fedora: AMD Phenom II 905e @ 4x2500 MHz, Raspberry Pi B 512 MB @ 1x800 MHz, Raspberry Pi B 256 MB @ 1x700 MHz
Debian: BeagleBoard xM @ 1x1000 MHz, Apple PowerMac G5 @ 2x1800 MHZ